Replace _Py_Identifier objects with interned strings

Summary:
_Py_Identifier is internal to CPython and it's been getting harder and harder to
access, see https://bugs.python.org/issue46541.

For most uses in CinderX we can initialize static local variables that will
lazily create interned Python strings.  It's not as efficient as _Py_Identifier,
but it's using the stable API so it'll be easier to maintain over time.

The places where we still have _Py_Identifier relate to using
`_PyObject_LookupSpecial` (in 3.12 it's renamed to `_PyObject_LookupSpecialId`).
There's no equivalent of that function that uses `PyObject*` values, we'll
likely have to implement that ourselves.

Reviewed By: DinoV

Differential Revision: D59936685

fbshipit-source-id: 2393fa5f5fff8205ff5203ce7e814b8e8f340971

Include/cpython/ceval.h

@@ -13,6 +13,7 @@ PyAPI_FUNC(int) _PyEval_SetAsyncGenFinalizer(PyObject *);
 PyAPI_FUNC(PyObject *) _PyEval_GetAsyncGenFinalizer(void);
 
 /* Helper to look up a builtin object */
+PyAPI_FUNC(PyObject *) _PyEval_GetBuiltin(PyObject *);
 PyAPI_FUNC(PyObject *) _PyEval_GetBuiltinId(_Py_Identifier *);
 /* Look at the current frame's (if any) code's co_flags, and turn on
    the corresponding compiler flags in cf->cf_flags.  Return 1 if any

Python/ceval.c

@@ -5675,19 +5675,22 @@ PyEval_GetBuiltins(void)
 
 /* Convenience function to get a builtin from its name */
 PyObject *
-_PyEval_GetBuiltinId(_Py_Identifier *name)
+_PyEval_GetBuiltin(PyObject *name)
 {
     PyThreadState *tstate = _PyThreadState_GET();
-    PyObject *attr = _PyDict_GetItemIdWithError(PyEval_GetBuiltins(), name);
-    if (attr) {
-        Py_INCREF(attr);
-    }
-    else if (!_PyErr_Occurred(tstate)) {
-        _PyErr_SetObject(tstate, PyExc_AttributeError, _PyUnicode_FromId(name));
+    PyObject *attr = PyObject_GetItem(PyEval_GetBuiltins(), name);
+    if (attr == NULL && _PyErr_ExceptionMatches(tstate, PyExc_KeyError)) {
+        _PyErr_SetObject(tstate, PyExc_AttributeError, name);
     }
     return attr;
 }
 
+PyObject *
+_PyEval_GetBuiltinId(_Py_Identifier *name)
+{
+    return _PyEval_GetBuiltin(_PyUnicode_FromId(name));
+}
+
 PyObject *
 PyEval_GetLocals(void)
 {