gh-116417: Add _testlimitedcapi C extension (#116419) Add a new C extension "_testlimitedcapi" which is only built with the limited C API. Move heaptype_relative.c and vectorcall_limited.c from Modules/_testcapi/ to Modules/_testlimitedcapi/. * configure: add _testlimitedcapi test extension. * Update generate_stdlib_module_names.py. * Update make check-c-globals. Co-authored-by: Erlend E. Aasland <erlend.aasland@protonmail.com>