bpo-46417: Clear more static types (GH-30796)

* Move PyContext static types into object.c static_types list.
* Rename PyContextTokenMissing_Type to _PyContextTokenMissing_Type
  and declare it in pycore_context.h.
* _PyHamtItems types are no long exported: replace PyAPI_DATA() with
  extern.

Python/pylifecycle.c

@@ -760,7 +760,7 @@ pycore_init_types(PyInterpreterState *interp)
         return status;
     }
 
-    status = _PyContext_InitTypes(interp);
+    status = _PyContext_Init(interp);
     if (_PyStatus_EXCEPTION(status)) {
         return status;
     }