Add C# 14 ExtensionMarkerAttribute

Author: siegfriedpammer

ICSharpCode.Decompiler/TypeSystem/Implementation/KnownAttributes.cs

@@ -116,11 +116,14 @@ public enum KnownAttribute
 
 		// C# 12 attributes:
 		InlineArray,
+
+		// C# 14 attributes:
+		ExtensionMarker,
 	}
 
 	public static class KnownAttributes
 	{
-		internal const int Count = (int)KnownAttribute.InlineArray + 1;
+		internal const int Count = (int)KnownAttribute.ExtensionMarker + 1;
 
 		static readonly TopLevelTypeName[] typeNames = new TopLevelTypeName[Count]{
 			default,
@@ -193,6 +196,8 @@ public static class KnownAttributes
 			new TopLevelTypeName("System.Runtime.CompilerServices", "RequiredMemberAttribute"),
 			// C# 12 attributes:
 			new TopLevelTypeName("System.Runtime.CompilerServices", "InlineArrayAttribute"),
+			// C# 14 attributes:
+			new TopLevelTypeName("System.Runtime.CompilerServices", "ExtensionMarkerAttribute"),
 		};
 
 		public static ref readonly TopLevelTypeName GetTypeName(this KnownAttribute attr)