[FEATURE] Add support for Groq

[Talha345]

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?

Groq is an inference provider and supports multiple types of models including Text to Text, Speech to Text, Vision, Reasoning etc.

Therefore it makes sense to add Groq and other inference providers as supported providers.

Proposed solution

Adding support for Groq. Could be bit tricky to since such platforms support various models with varying capabilities.

Why this belongs in RubyLLM

Currently there are no inference providers available via RubyLLM and there is no way to add a custom provider.