gh-93939: Add script to check extension modules (#94545)

Add script ``Tools/scripts/check_modules.py`` to check and validate builtin
and shared extension modules. The script also handles ``Modules/Setup`` and
will eventually replace ``setup.py``.

Co-authored-by: Victor Stinner <vstinner@python.org>
Co-authored-by: Erlend Egeberg Aasland <erlend.aasland@protonmail.com>