[FEATURE] Add support for xAI

[DaveMcMartin]

Scope check

• This is core LLM communication (not application logic)
• This benefits most users (not just my use case)
• This can't be solved in application code with current RubyLLM
• I read the Contributing Guide

Due diligence

• I searched existing issues
• I checked the documentation

What problem does this solve?

There is no integration with Grok from XAI and open ai API is not compatible

Proposed solution

Add xAI API support to RubyLLM

Why this belongs in RubyLLM

xAI support fits in RubyLLM to keep things simple for everyone.

If no one is working on this already I'm happy to open a PR.

[infinityrobot]

@DaveMcMartin I've been working on this – should have a PR ready within the next week or so!

[crmne]

@infinityrobot would love to see it!

[iraszl]

Good idea. Hope to see it soon! 🙌

[infinityrobot]

Just cleaning up the PR now, should be here within next few days. Also cleaning up my Cohere Provider PR too to use the new Provider Class patterns too.

[infinityrobot]

Hi all, I have pushed a draft PR to #373. I need to fix up some error / chunk handling still and refresh VCRs but core implementation is there. Should be able to get to wrapping things up so we're in a position for full review after the weekend.

[infinityrobot]

This is now good for review in #373!