Langchain Chat Improvements

[KevinLuong96]

This PR

• fixes python interpreter using langchain. Currently tool use using Cohere API passes in a dictionary with a code key, but Langchain passes in code string as the parameter. This PR adds a langchain wrapper to call the function with the right parameters
• Fixes streaming of langchain by removing async
• Passes the results of the langchain events through to frontend
• Sends a stream start event when the langchain Chat stream starts

Screen.Recording.2024-04-24.at.3.34.01.PM.mov

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