Message 411987 - Python tracker

> `_Py_Identifier` has been useful but at this point there is a faster and simpler approach we could take as a replacement: statically initialize the objects as fields on `_PyRuntimeState` and reference them directly through a macro.

This change is going to break projects in the wild. Yes, people use the _Py_IDENTIFIER(), _PyUnicode_FromId() and other "Id" variant of many functions in 3rd party projects.

Is it possible to keep runtime initialization if this API is used by 3rd party code?