Expose non-template versions of vararg methods

[kevinresol]

Godot version

4.3.stable

godot-cpp version

4.3

System information

MacOS 15.2

Issue description

For custom scripting support and other dynamic uses, it would be nice to expose vararg methods as non-templated.

Currently, the dynamic (non-template) version (<fn>_internal) for classes and utility_functions already exists, although marked private: . As for builtin_classes there are no equivalent, the closes thing would be the private _method_bindings struct but those are raw method pointers doesn't give us nice signature and return value handling.

If this suggestion is accepted, I can raise a PR to remove the private accessor for classes and utility_functions, and refactor builtin_classes bindings to expose the corresponding *_internal methods.

Steps to reproduce

N/A

Minimal reproduction project

N/A