[FEATURE] Add OpenAI vector store support to upsonic[RAG]

I would like to request a feature enhancement to Upsonic's RAG support. I would like to be able to point my agent's knowledge base against an OpenAI vectorID.

Ideally, this enhancement would be based on OpenAI's newer file_search tool with similar functionality. I should be able to search across the entire vector store without having to specify a specific filename in the RAG database.

thanks for your consideration!