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>

Include/unicodeobject.h

@@ -982,14 +982,14 @@ PyAPI_FUNC(int) TyUnicode_Equal(TyObject *str1, TyObject *str2);
 
    Possible values for op:
 
-     Ty_GT, Ty_GE, Ty_EQ, Ty_NE, Ty_LT, Ty_LE
+     Py_GT, Py_GE, Py_EQ, Py_NE, Py_LT, Py_LE
 
 */
 
 PyAPI_FUNC(TyObject *) TyUnicode_RichCompare(
     TyObject *left,             /* Left string */
     TyObject *right,            /* Right string */
-    int op                      /* Operation: Ty_EQ, Ty_NE, Ty_GT, etc. */
+    int op                      /* Operation: Py_EQ, Py_NE, Py_GT, etc. */
     );
 
 /* Apply an argument tuple or dictionary to a format string and return