Add RAG search capabilities

[dgarnitz]

Highly recommended to do this issue ticket first

What To Build

• An endpoint add to the api that allows the user to perform RAG with a given text-only search term. Use the following prompt for the RAG

retrieval_prompt = (
            "Context information is below.\n"
            "---------------------\n"
            "{context_str}\n"
            "---------------------\n"
            "Given the context information and not prior knowledge, "
            "answer the query.\n"
            "Query: {query_str}\n"
            "Answer: "
        )

• Use the semantic search endpoint created here
• No reranker is needed yet
• No query pre-processing is needed yet