LLM Observability: Add optional Langfuse support

[aiakubovich]

Hi! We use the AOAI app extensively, but it lacks LLM observability functionality. There should be an easy way to gather user interactions within the AOAI app. Langfuse is an open-source LLM observability platform that supports prompt logging. It offers native integration with OpenAI library which can be achieved by adding just a few lines of code to the underlying Python script. I am wondering whether it would be feasible to add optional Langfuse support into the AOAI app, as it seems that only minimal changes are required (a few variables for the Azure Web App and few lines in the AOAI app code). If this is ok, I can attempt to create a pull request for it.

[rochaktarika123]

Was this done? I think it will be very useful because I havent see much on the logging aspect of the prompts and completions