Clean up border code

Removed caching that really didn't do anything anymore.

src/Spectre.Console/Rendering/Borders/Boxes/AsciiBoxBorder.cs

@@ -8,7 +8,7 @@ namespace Spectre.Console.Rendering
     public sealed class AsciiBoxBorder : BoxBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(BoxBorderPart part)
+        public override string GetPart(BoxBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Boxes/DoubleBoxBorder.cs

@@ -8,7 +8,7 @@ namespace Spectre.Console.Rendering
     public sealed class DoubleBoxBorder : BoxBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(BoxBorderPart part)
+        public override string GetPart(BoxBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Boxes/HeavyBoxBorder.cs

@@ -11,7 +11,7 @@ namespace Spectre.Console.Rendering
         public override BoxBorder? SafeBorder => BoxBorder.Square;
 
         /// <inheritdoc/>
-        protected override string GetBorderPart(BoxBorderPart part)
+        public override string GetPart(BoxBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Boxes/NoBoxBorder.cs

@@ -6,7 +6,7 @@ namespace Spectre.Console.Rendering
     public sealed class NoBoxBorder : BoxBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(BoxBorderPart part)
+        public override string GetPart(BoxBorderPart part)
         {
             return " ";
         }

src/Spectre.Console/Rendering/Borders/Boxes/RoundedBoxBorder.cs

@@ -11,7 +11,7 @@ namespace Spectre.Console.Rendering
         public override BoxBorder? SafeBorder => BoxBorder.Square;
 
         /// <inheritdoc/>
-        protected override string GetBorderPart(BoxBorderPart part)
+        public override string GetPart(BoxBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Boxes/SquareBoxBorder.cs

@@ -8,7 +8,7 @@ namespace Spectre.Console.Rendering
     public sealed class SquareBoxBorder : BoxBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(BoxBorderPart part)
+        public override string GetPart(BoxBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/Ascii2TableBorder.cs

@@ -8,7 +8,7 @@ namespace Spectre.Console.Rendering
     public sealed class Ascii2TableBorder : TableBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/AsciiDoubleHeadTableBorder.cs

@@ -8,7 +8,7 @@ namespace Spectre.Console.Rendering
     public sealed class AsciiDoubleHeadTableBorder : TableBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/AsciiTableBorder.cs

@@ -8,7 +8,7 @@ namespace Spectre.Console.Rendering
     public sealed class AsciiTableBorder : TableBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/DoubleEdgeTableBorder.cs

@@ -8,7 +8,7 @@ namespace Spectre.Console.Rendering
     public sealed class DoubleEdgeTableBorder : TableBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/DoubleTableBorder.cs

@@ -8,7 +8,7 @@ namespace Spectre.Console.Rendering
     public sealed class DoubleTableBorder : TableBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/HeavyEdgeTableBorder.cs

@@ -11,7 +11,7 @@ namespace Spectre.Console.Rendering
         public override TableBorder? SafeBorder => TableBorder.Square;
 
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/HeavyHeadTableBorder.cs

@@ -11,7 +11,7 @@ namespace Spectre.Console.Rendering
         public override TableBorder? SafeBorder => TableBorder.Square;
 
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/HeavyTableBorder.cs

@@ -11,7 +11,7 @@ namespace Spectre.Console.Rendering
         public override TableBorder? SafeBorder => TableBorder.Square;
 
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/HorizontalTableBorder.cs

@@ -8,7 +8,7 @@ namespace Spectre.Console.Rendering
     public sealed class HorizontalTableBorder : TableBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/MarkdownTableBorder.cs

@@ -11,7 +11,7 @@ namespace Spectre.Console.Rendering
     public sealed class MarkdownTableBorder : TableBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {
@@ -57,39 +57,39 @@ namespace Spectre.Console.Rendering
                 if (padding.Left > 0)
                 {
                     // Left padding
-                    builder.Append(" ".Multiply(padding.Left));
+                    builder.Append(" ".Repeat(padding.Left));
                 }
 
                 var justification = columns[columnIndex].Alignment;
                 if (justification == null)
                 {
                     // No alignment
-                    builder.Append(center.Multiply(columnWidth));
+                    builder.Append(center.Repeat(columnWidth));
                 }
                 else if (justification.Value == Justify.Left)
                 {
                     // Left
                     builder.Append(':');
-                    builder.Append(center.Multiply(columnWidth - 1));
+                    builder.Append(center.Repeat(columnWidth - 1));
                 }
                 else if (justification.Value == Justify.Center)
                 {
                     // Centered
                     builder.Append(':');
-                    builder.Append(center.Multiply(columnWidth - 2));
+                    builder.Append(center.Repeat(columnWidth - 2));
                     builder.Append(':');
                 }
                 else if (justification.Value == Justify.Right)
                 {
                     // Right
-                    builder.Append(center.Multiply(columnWidth - 1));
+                    builder.Append(center.Repeat(columnWidth - 1));
                     builder.Append(':');
                 }
 
                 // Right padding
                 if (padding.Right > 0)
                 {
-                    builder.Append(" ".Multiply(padding.Right));
+                    builder.Append(" ".Repeat(padding.Right));
                 }
 
                 if (!lastColumn)

src/Spectre.Console/Rendering/Borders/Tables/MinimalDoubleHeadTableBorder.cs

@@ -8,7 +8,7 @@ namespace Spectre.Console.Rendering
     public sealed class MinimalDoubleHeadTableBorder : TableBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/MinimalHeavyHeadTableBorder.cs

@@ -11,7 +11,7 @@ namespace Spectre.Console.Rendering
         public override TableBorder? SafeBorder => TableBorder.Minimal;
 
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/MinimalTableBorder.cs

@@ -8,7 +8,7 @@ namespace Spectre.Console.Rendering
     public sealed class MinimalTableBorder : TableBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/NoTableBorder.cs

@@ -9,7 +9,7 @@ namespace Spectre.Console.Rendering
         public override bool Visible => false;
 
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return " ";
         }

src/Spectre.Console/Rendering/Borders/Tables/RoundedTableBorder.cs

@@ -11,7 +11,7 @@ namespace Spectre.Console.Rendering
         public override TableBorder? SafeBorder => TableBorder.Square;
 
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/SimpleHeavyTableBorder.cs

@@ -11,7 +11,7 @@ namespace Spectre.Console.Rendering
         public override TableBorder? SafeBorder => TableBorder.Simple;
 
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/SimpleTableBorder.cs

@@ -8,7 +8,7 @@ namespace Spectre.Console.Rendering
     public sealed class SimpleTableBorder : TableBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {

src/Spectre.Console/Rendering/Borders/Tables/SquareTableBorder.cs

@@ -8,7 +8,7 @@ namespace Spectre.Console.Rendering
     public sealed class SquareTableBorder : TableBorder
     {
         /// <inheritdoc/>
-        protected override string GetBorderPart(TableBorderPart part)
+        public override string GetPart(TableBorderPart part)
         {
             return part switch
             {