Support vararg for Engine classes

[fuzzybinary]

Vararg methods cannot be called with Ptr calls in Godot, and attempting to get them returns a null address for the function (which obviously crashes).

This should work okay for Engine classes which are already not using ptr calls, but the generated code have the funcitons take a List<Variant> as their paraemter list, defaulted to [], and make sure this is passed as the arguments to the vararg function