Support Codex CLI as API Provider

[bharadwajpro]

• If someone has ChatGPT Plus or Pro, they can use Codex CLI with their subscription. Reference
• Support "Codex CLI" as API Provider just like how "Claude Code" is currently present as an API Provider
• There is already "OpenAI" as an API Provider but that works with API Keys. I am looking for a feature where Roo Code supports "Codex CLI" and people can use their regular ChatGPT subscription for coding as well

[bharadwajpro]

Seems like when you are codex login it generates a token at ~/.codex/auth.json. The token has OPENAI_API_KEY in it. Perhaps we can use this somehow.