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.

まず、この issue で参照されている _Py_Dealloc() と Py_DECREF() のエントリポイントを調査し、次に関連するコンテキストについて issue 97922 を読みます。提案されている Py_SAFE_DECREF() アプローチと、Py_DECREF() 自体を変更する場合を、拡張モジュールのオブジェクトの解放に対する影響も含めて比較します。結果として生じる解放動作をカバーした、根拠のある設計を選択して実装できれば完了です。