Issue #19512: add _PyUnicode_CompareWithId() function

_PyUnicode_CompareWithId() is faster than PyUnicode_CompareWithASCIIString()
when both strings are equal and interned.

Add also _PyId_builtins identifier for "builtins" common string.

Objects/unicodeobject.c

@@ -10565,6 +10565,15 @@ PyUnicode_Compare(PyObject *left, PyObject *right)
     return -1;
 }
 
+int
+_PyUnicode_CompareWithId(PyObject *left, _Py_Identifier *right)
+{
+    PyObject *right_str = _PyUnicode_FromId(right);   /* borrowed */
+    if (right_str == NULL)
+        return -1;
+    return PyUnicode_Compare(left, right_str);
+}
+
 int
 PyUnicode_CompareWithASCIIString(PyObject* uni, const char* str)
 {