Add ByRefLikeGenerics to runtime features (#250)

***NO_CI***

Author: josesimoes

nanoFramework.CoreLibrary/System/Runtime/CompilerServices/RuntimeFeature.cs

@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
 namespace System.Runtime.CompilerServices
@@ -13,17 +13,22 @@ public static partial class RuntimeFeature
         /// </summary>
         public const string DefaultImplementationsOfInterfaces = nameof(DefaultImplementationsOfInterfaces);
 
+        /// <summary>
+        /// Represents a runtime feature where byref-like types can be used in Generic parameters.
+        /// </summary>
+        public const string ByRefLikeGenerics = nameof(ByRefLikeGenerics);
+
         /// <summary>
         /// Checks whether a certain feature is supported by the Runtime.
         /// </summary>
         public static bool IsSupported(string feature)
         {
-            if (feature == DefaultImplementationsOfInterfaces)
+            return feature switch
             {
-                return true;
-            }
-
-            return false;
+                ByRefLikeGenerics or
+                DefaultImplementationsOfInterfaces => true,
+                _ => false,
+            };
         }
     }
 }