add generic virtual functions

[wolfcomp]

Note when using this generator:

• Only Fields and VirtualFunctions are allowed inside a generic type
• MemberFunctions cannot be used inside a generic type due to registering the function isn't possible with generic types. CPP will always create different functions for the different templates, if you need to attach a member function for a type that comes from a template function a new struct that is not a generic must be created.

Currently, this won't work due to loading of generics doesn't permit explicit struct layout https://github.com/dotnet/runtime/issues/97526 Hopefully this will be allowed at some point with unmanaged constraint as we only require to handle CPP to C# conversion.