feat(text_to_sql): add include_entire_schema and only_these_objects o…

[jgpruitt]

…ptions to text-to-sql

1. "Normal mode" semantic search

select ai.text_to_sql('How many flights arrived in Houston, TX in June 2024?');

2. include_entire_schema - bypasses search and includes the entire schema in the prompt

select ai.text_to_sql('How many flights arrived in Houston, TX in June 2024?'
, config=>ai.text_to_sql_openai(model=>'o3-mini', include_entire_schema=>true)
);

3. only_these_objects - bypasses search and only includes the specific tables/views in the prompt

select ai.text_to_sql('How many flights arrived in Houston, TX in June 2024?'
, config=>ai.text_to_sql_openai(model=>'o3-mini', only_these_objects=>array['postgres_air.flight', 'postgres_air.airport']::regclass[])
);

only_these_objects does not allow you to specify functions. I doubt we'll need that, and I doubt we'll keep this functionality. If we need to, we can add it later.

Also, we now extract the estimated cost and estimated rows from the query plan and return them