feat: Feature request: Conversational Retrieval QA

[nidzola]

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Description

• implementing https://python.langchain.com/docs/modules/chains/popular/chat_vector_db
• closing issue Feature request: Conversational Retrieval QA #205

[ccbond]

looks great!

[tmc]

Can you add an example demonstrating use?

[nidzola]

Can you add an example demonstrating use?

I've added a unit test, which is demoing the usage, not sure if you were thinking to have something else?