feat(llm/groq): add disable_tool_validation option to LLM configuration

[youssmox]

Summary

• Added support for propagating the Groq-specific disable_tool_validation flag through livekit.plugins.openai.LLM, storing it in _LLMOptions.
• Forward the flag in LLM.chat only when the client’s base URL points at Groq, raising a clear error otherwise to avoid misconfiguration.
• This ensures the Groq plugin can opt out of tool validation without breaking other OpenAI-compatible providers.

Testing

• Not run (feature is configuration-only; recommend running Groq integration test/smoke before merge).

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[chenghao-mou]

Thanks for creating the PR!

This flag should be an extra body parameter instead of a function parameter in extra/extra_kwargs. Otherwise, it will throw errors like:

TypeError: AsyncCompletions.create() got an unexpected keyword argument 'disable_tool_validation'