gh-108494: Argument Clinic partial supports of Limited C API (#108495)

Argument Clinic now has a partial support of the
Limited API:

* Add --limited option to clinic.c.
* Add '_testclinic_limited' extension which is built with
  the limited C API version 3.13.
* For now, hardcode in clinic.py that "_testclinic_limited.c" targets
  the limited C API.