corlib: Implement System.Type.GetTypeFromCLSID.

This isn't the way native does it (I've noticed that native always returns a class named System.__ComObject from the mscorlib assembly, which is also somehow a different class for each clsid and is a direct subclass of MarshalByRefObject), but I think it's as close as can be achieved without messing with the internals of how types are implemented. I believe developers rely on the type being called System.__ComObject, but I'm hoping they're not picky about its assembly or superclasses.