Use langchain for longer prompting

[finnless]

https://github.com/openai/openai-cookbook/blob/main/examples/vector_databases/pinecone/GPT4_Retrieval_Augmentation.ipynb
https://github.com/openai/openai-cookbook/blob/main/examples/Question_answering_using_embeddings.ipynb
https://github.com/chroma-core/chroma
https://github.com/openai/chatgpt-retrieval-plugin
https://blog.langchain.dev/langchain-chat/