Add LiteLLM - support for Ollama, Vertex AI, Gemini, Anthropic, Bedrock (100+LLMs)

[ishaan-jaff]

Description

This PR adds support for the above mentioned LLMs using LiteLLM https://github.com/BerriAI/litellm/
LiteLLM is a lightweight package to simplify LLM API calls - use any llm as a drop in replacement for gpt-4o.

• Resolves Support model providers other than OpenAI and Azure #657

Example

from litellm import completion
import os

## set ENV variables
os.environ["OPENAI_API_KEY"] = "your-openai-key"
os.environ["ANTHROPIC_API_KEY"] = "your-cohere-key"

messages = [{ "content": "Hello, how are you?","role": "user"}]

# openai call
response = completion(model="openai/gpt-4o", messages=messages)

# anthropic call
response = completion(model="anthropic/claude-3-sonnet-20240229", messages=messages)
print(response)

Response (OpenAI Format)

{
    "id": "chatcmpl-565d891b-a42e-4c39-8d14-82a1f5208885",
    "created": 1734366691,
    "model": "claude-3-sonnet-20240229",
    "object": "chat.completion",
    "system_fingerprint": null,
    "choices": [
        {
            "finish_reason": "stop",
            "index": 0,
            "message": {
                "content": "Hello! As an AI language model, I don't have feelings, but I'm operating properly and ready to assist you with any questions or tasks you may have. How can I help you today?",
                "role": "assistant",
                "tool_calls": null,
                "function_call": null
            }
        }
    ],
    "usage": {
        "completion_tokens": 43,
        "prompt_tokens": 13,
        "total_tokens": 56,
        "completion_tokens_details": null,
        "prompt_tokens_details": {
            "audio_tokens": null,
            "cached_tokens": 0
        },
        "cache_creation_input_tokens": 0,
        "cache_read_input_tokens": 0
    }
}

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Related Issues

#657

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Proposed Changes

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Checklist

• I have tested these changes locally.
• I have reviewed the code changes.
• I have updated the documentation (if necessary).
• I have added appropriate unit tests (if applicable).

Additional Notes

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[ishaan-jaff]

Can I get a review on this @natoverse ?