Custom authentication

What feature would you like to see?

Hi,

I've noticed a PR which seems to start adding support for custom OAuth?
https://github.com/openai/codex/pull/3531/files#diff-210b46650ab2390869ab63aac66ce8c2fa0abe1a59c20b71bd4f4dbf9729a0acR137-R150

Any idea if this is in plan to be added?
As we would need this feature, basically use Codex but with our custom OAuth provider and then have codex connect to our custom API endpoint that basically just checks for auth and then proxies the requests to OpenAI API.

Additional information

_No response_