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>

Modules/_opcode.c

@@ -217,7 +217,7 @@ _opcode_get_specialization_stats_impl(TyObject *module)
 #ifdef Ty_STATS
     return _Ty_GetSpecializationStats();
 #else
-    Ty_RETURN_NONE;
+    Py_RETURN_NONE;
 #endif
 }