Sharpen type annotation of `_get_arg_id_to_arg_and_arg_id_to_descr`

According to the type listed `args: tuple[Any, ...]`, args should be able to support an object type. However, it does not. Passing in an object that is not an `pt.Array` or `scalar` or `ArrayContainer` returns an error message. I think we should just return the descriptor as the position of the object within the `args` tuple.