[WIP] prompt preprocessing

[andrewfulton9]

I added the basic structure for a preprocessor. There is still a lot to do here. I have an example of using it in a notebook in the top level folder of the repository. I will remove it before moving this PR from a draft. It has a very simple preprocessor that uses chatgpt to reword the prompt. I ended up calling chatgpt outside of the ragna openai assistant so the ragna specific instruction wouldn't be included. It may be worth opening up the assistant interface a bit to allow more varied use of the assistants. I also havn't addressed saving the QueryProcessor information to the database yet.