Implement Type.IsTypeDefinition property on CoreCLR (dotnet/coreclr#11355)

This api was just approved.

https://github.com/dotnet/corefx/issues/17345

Signed-off-by: dotnet-bot-corefx-mirror <dotnet-bot@microsoft.com>

Author: atsushikan

src/Common/src/CoreLib/System/Reflection/TypeDelegator.cs

@@ -100,6 +100,7 @@ protected override PropertyInfo GetPropertyImpl(string name, BindingFlags bindin
 
         protected override TypeAttributes GetAttributeFlagsImpl() => typeImpl.Attributes;
 
+        public override bool IsTypeDefinition => typeImpl.IsTypeDefinition;
         public override bool IsSZArray => typeImpl.IsSZArray;
 
         protected override bool IsArrayImpl() => typeImpl.IsArray;

src/Common/src/CoreLib/System/Type.cs

@@ -32,6 +32,7 @@ protected Type() { }
         public override Type ReflectedType => null;
         public abstract Type UnderlyingSystemType { get; }
 
+        public virtual bool IsTypeDefinition { get { throw NotImplemented.ByDesign; } }
         public bool IsArray => IsArrayImpl();
         protected abstract bool IsArrayImpl();
         public bool IsByRef => IsByRefImpl();