Deferring side effecting code in `_Py_Dealloc()`

Currently _Py_Dealloc() can call arbitrary code, and since _Py_Dealloc() can be called by any Py_DECREF() is means that Py_DECREF() can call arbitrary code. Py_DECREF() is everywhere, so it impairs our ability to reason about about the behavior of code.
This problem is not as severe as https://github.com/python/cpython/issues/97922, but is still worth fixing, especially as it will impair our ability to optimize traces for 3.12.

We can either make a Py_SAFE_DECREF() to be used internally, or change Py_DECREF() to defer all potentially side-effecting deallocation functions.

It is not clear which is the best option. Changing Py_DECREF() is simple, and certainly easy to reason about, but might delay deallocation of extension module objects for too long.

Comienza examinando los puntos de entrada _Py_Dealloc() y Py_DECREF() mencionados en este issue; después, lee el issue 97922 para conocer el contexto relacionado. Compara el enfoque propuesto de Py_SAFE_DECREF() con cambiar Py_DECREF() directamente, incluido el efecto sobre la desasignación de objetos de los módulos de extensión. Se considera completado cuando se haya seleccionado e implementado un diseño justificado, con cobertura del comportamiento de desasignación resultante.