Fix @auto_docstring crash with from __future__ import annotations in _process_kwargs_parameters

[rpathade]

What does this PR do?

Fixes _process_kwargs_parameters crashing with AttributeError when @auto_docstring is applied in a module that uses from __future__ import annotations.

Fixes #45103

Root cause

from __future__ import annotations defers all annotations to strings at runtime. _process_kwargs_parameters accessed kwarg_param.annotation.__args__ directly, which fails when the annotation is a string instead of a type object:

# annotation is "Optional[IsaacKwargs]" (str), not the actual type — crashes here
if kwarg_param.annotation.__args__[0].__name__ not in BASIC_KWARGS_TYPES: