Search image data from `/api/conversation/custom`

[adamdougal]

Required by https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/issues/323

Description

When calling the /api/conversation/custom endpoint, generate embeddings of the question using computer vision and query the image embeddings using the question embeddings. We should continue to create question embeddings using text-embeddings-ada-002 in addition to be used to search the image description.

Tasks

• [x] Stop using langchain in the quesiton answer tool and post prompt tool
• [x] Generate question embeddings using computer vision
• [x] Query the search index using the generated embeddings
• [x] Pass any returned images to gpt-4-vision along with the chat
• [ ] Add a limit on the number of images passed to vision
• [ ] Update post answering prompt to include images