Add Layout widget (#1041)

* Add width to panels
* Add height to panels
* Replace RenderContext with RenderOptions
* Remove exclusivity from alternative buffer
* Add Layout widget
* Add Align widget

examples/Console/Layout/Layout.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net7.0</TargetFramework>
+    <ExampleTitle>Layout</ExampleTitle>
+    <ExampleDescription>Demonstrates how to use layouts.</ExampleDescription>
+    <ExampleGroup>Widgets</ExampleGroup>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\Shared\Shared.csproj" />
+  </ItemGroup>
+
+</Project>

examples/Console/Layout/Program.cs

@@ -0,0 +1,60 @@
+using System;
+using Spectre.Console;
+
+namespace Layouts;
+
+public static class Program
+{
+    public static void Main()
+    {
+        var layout = CreateLayout();
+        AnsiConsole.Write(layout);
+
+        Console.ReadKey(true);
+    }
+
+    private static Layout CreateLayout()
+    {
+        var layout = new Layout();
+
+        layout.SplitRows(
+            new Layout("Top")
+                .SplitColumns(
+                    new Layout("Left")
+                        .SplitRows(
+                            new Layout("LeftTop"),
+                            new Layout("LeftBottom")),
+                    new Layout("Right").Ratio(2),
+                    new Layout("RightRight").Size(3)),
+            new Layout("Bottom"));
+
+        layout["LeftBottom"].Update(
+            new Panel("[blink]PRESS ANY KEY TO QUIT[/]")
+                .Expand()
+                .BorderColor(Color.Yellow)
+                .Padding(0, 0));
+
+        layout["Right"].Update(
+            new Panel(
+                new Table()
+                    .AddColumns("[blue]Qux[/]", "[green]Corgi[/]")
+                    .AddRow("9", "8")
+                    .AddRow("7", "6")
+                    .Expand())
+            .Header("A [yellow]Table[/] in a [blue]Panel[/] (Ratio=2)")
+            .Expand());
+
+        layout["RightRight"].Update(
+            new Panel("Explicit-size-is-[yellow]3[/]")
+                .BorderColor(Color.Yellow)
+                .Padding(0, 0));
+
+        layout["Bottom"].Update(
+        new Panel(
+                new FigletText("Hello World"))
+            .Header("Some [green]Figlet[/] text")
+            .Expand());
+
+        return layout;
+    }
+}