feat: add protocol method for session/set_config_option

[Nemtecl]

Summary

Add protocol method for session/set_config_option

Related issues

#67

Testing

• Added test case in tests/conftests.py
• Added test case in tests/tests_rpc.py
• Ran make test locally

Docs & screenshots

https://agentclientprotocol.com/rfds/session-config-options

Checklist

• Conventional Commit title (e.g. feat:, fix:).
• Tests cover the change or are not required (explain above).
• Docs/examples updated when behaviour is user-facing.
• Schema regenerations (make gen-all) are called out if applicable.

[PsiACE]

thanks, lgtm

[Nemtecl]

Thanks @PsiACE 🙏

Do you think we can do a quick 0.8.1 release ?
From what I see, nothing has been merged since, and it'd fix #67 !

I'm looking forward to test this for Mistral Vibe 😄