[Mem0] Langchain model integration

[valentimarco]

🚀 The feature

Would be great to have a langchain integration! Why? Is great to use official library/clients but at the same time I don't want to create 300 objects for different library for the same llm/embedder provider!

Langchain provide 3 simple methods (invoke for llm and embed_query or embed_documents for embedders) to interact with the model.

If likes, i would create a PR with a preview of what discuss!

Great work btw <3

Motivation, pitch

I want to integrate the mem0 library in a project where we use langchain (unfortunately XD). At the moment, the only way is to extract config.