implement text-to-sql cache

[lostmygithubaccount]

right now, a bot will always generate new SQL even if it (in the current or previous session) has seen the same text and correctly generated SQL

primarily for demo purposes, we should enable attaching a cache database w/:

• text
• SQL
• accuracy_score (?)

we would need some way of manually populated this database (perhaps outside the scope of Ibis Birdbrain) and adding to it as new queries are seen, w/ the user somehow able to give an accuracy score/delete incorrect generations

[lostmygithubaccount]

potential implementations:

• exact string match
• Levenstein distance
• embeddings match
• full text search extension (https://duckdb.org/docs/extensions/full_text_search.html)