Refactor CoreCLR runtime into explicit dotnet api instead of mocking mono api

Required by platforms that will use mono under the hood for .Net 7
New `USE_CSHARP` define for C# ability
Engine doesn't use `mono_*` apis directly but via MCore/MClass/MMethod/ apis

Source/Engine/Localization/CultureInfo.h

@@ -11,6 +11,7 @@
 API_CLASS(InBuild, Namespace="System.Globalization") class FLAXENGINE_API CultureInfo
 {
     DECLARE_SCRIPTING_TYPE_MINIMAL(CultureInfo);
+
 private:
     void* _data;
     int32 _lcid;
@@ -64,11 +65,6 @@ public:
     /// </summary>
     const String& GetEnglishName() const;
 
-    /// <summary>
-    /// Returns true if culture uses right-to-left (RTL) text layout. Otherwise it's more common left-to-right.
-    /// </summary>
-    bool IsRightToLeft() const;
-
     String ToString() const;
     bool operator==(const CultureInfo& other) const;
 };