Refactor enum value retrieval to use EnumUtils for better compatibility with NetStandard 2.0 and AOT

src/Spectre.Console/Internal/DecorationTable.cs

@@ -54,8 +54,7 @@ internal static class DecorationTable
     {
         var result = new List<string>();
 
-        Enum.GetValues(typeof(Decoration))
-            .Cast<Decoration>()
+        EnumUtils.GetValues<Decoration>()
             .Where(flag => (decoration & flag) != 0)
             .ForEach(flag =>
             {

src/Spectre.Console/Internal/FileSize.cs

@@ -140,7 +140,7 @@ internal struct FileSize
             bytes *= 8;
         }
 
-        foreach (var prefix in (FileSizePrefix[])Enum.GetValues(typeof(FileSizePrefix)))
+        foreach (var prefix in EnumUtils.GetValues<FileSizePrefix>())
         {
             // Trying to find the largest unit, that the number of bytes can fit under. Ex. 40kb < 1mb
             if (bytes < Math.Pow((int)_prefixBase, (int)prefix + 1))

src/Spectre.Console/Internal/Polyfill/EnumHelpers.cs

@@ -0,0 +1,15 @@
+namespace Spectre.Console;
+
+internal static class EnumUtils
+{
+    public static T[] GetValues<T>()
+        where T : struct, Enum
+    {
+        return
+#if NET6_0_OR_GREATER
+        Enum.GetValues<T>();
+#else
+            (T[])Enum.GetValues(typeof(T));
+#endif
+    }
+}