Add support for async database interaction to enable async search

[lsorber]

Async drivers:

• SQLite: https://github.com/omnilib/aiosqlite
• PostgreSQL: https://github.com/MagicStack/asyncpg

Also, we can avoid having to duplicate all code for sync and async implementations with https://asyncer.tiangolo.com/tutorial/syncify-no-raise/#run-async-code-from-mainly-blocking-code.

[undo76]

This will also solve problems with chainlit, as it is using async for the persistence DB operations (conversation history and feedback).

[lsorber]

Yes, this would be an awesome upgrade!