gh-90928: Statically Initialize the Keywords Tuple in Clinic-Generated Code (gh-95860)

We only statically initialize for core code and builtin modules.  Extension modules still create
the tuple at runtime.  We'll solve that part of interpreter isolation separately.

This change includes generated code. The non-generated changes are in:

* Tools/clinic/clinic.py
* Python/getargs.c
* Include/cpython/modsupport.h
* Makefile.pre.in (re-generate global strings after running clinic)
* very minor tweaks to Modules/_codecsmodule.c and Python/Python-tokenize.c

All other changes are generated code (clinic, global strings).

Author: ericsnowcurrently

Include/cpython/modsupport.h

@@ -51,6 +51,7 @@ PyAPI_FUNC(PyObject **) _Py_VaBuildStack(
     Py_ssize_t *p_nargs);
 
 typedef struct _PyArg_Parser {
+    int initialized;
     const char *format;
     const char * const *keywords;
     const char *fname;