Fix incorrect replacements in Py_ to Ty_ renaming

Fixed several macros and constants that should not have been renamed:
- _Py_CAST, _Py_NULL, _Py_RVALUE (internal utility macros)
- Py_UNUSED (unused parameter macro)
- Py_EQ, Py_NE, Py_LT, Py_LE, Py_GT, Py_GE (comparison constants)
- Py_RETURN_* macros (NONE, TRUE, FALSE, NOTIMPLEMENTED, RICHCOMPARE)
- Py_READONLY, Py_ULL, Py_CONTEXT_SWITCHED
- TyGC_Head in generated clinic files

Build is still in progress with some remaining issues to resolve.

Co-authored-by: johndoe6345789 <224850594+johndoe6345789@users.noreply.github.com>

Python/errors.c

@@ -1608,7 +1608,7 @@ _TyErr_WriteUnraisableDefaultHook(TyObject *args)
     if (write_unraisable_exc(tstate, exc_type, exc_value, exc_tb, err_msg, obj) < 0) {
         return NULL;
     }
-    Ty_RETURN_NONE;
+    Py_RETURN_NONE;
 }