Support function calling LLMs to CrewAI agents

[areibman]

🚀 Feature Request

💡 Got a brilliant idea? Currently, Agents only track the main llm parameter. However, in Crew, you can pass in a function_calling_llm argument and track that as well.

🤔 Is your feature request related to a problem? Function calling LLMs are like a secondary LLM used by agents specifically for picking function calls. This wasn't a pattern we'd thought was required at first, but now it's clear that it's an emerging paradigm.

🎉 Describe the solution you'd like Add function calling LLMs to the agent