WIP feat: add chatgpt auth login

[ScriptedAlchemy]

This pull request enhances the authentication flow for the OpenAI provider in the CLI, giving users a choice between logging in with ChatGPT (OAuth) or using an API key. It also introduces a more robust OAuth login implementation and adds a custom header for requests to the OpenAI API. The most important changes are grouped below:

OpenAI Authentication Improvements:

• Added a prompt for OpenAI users to choose between signing in with ChatGPT (OAuth) or using an API key during auth login. If "Sign in with ChatGPT" is selected, the new OAuth flow is initiated.
• Implemented a complete OAuth login flow for OpenAI, including PKCE challenge generation, local callback server, token exchange, and storing both API and refresh tokens.
• Improved handling for API key authentication, including validation and proper storage of credentials. [1] [2]

Provider Request Customization:

• Added an originator: "codex_cli_rs" header to all OpenAI API requests to help identify requests coming from this codex (might not be needed, will confirm).

[ScriptedAlchemy]

in china right now so i cannot properly test authenticating in with a new token, but will check it in the office on monday

[asafyish]

Does it allow us to use the pro package quota ?

[goniz]

I might be missing this in the code, but what about the token refresh logic?

[shantur]

This would be nice to have in if it allows to use the Pro quota