Feat: DuckDB extension config to support community extensions

[rubenvereecken]

This now supports alternative DuckDB extension repositories like the built-in community.

gateways:
  bq:
    connection:
      type: duckdb
      extensions:
        - name: bigquery
          repository: community
          force_install: true
      catalogs:
        mem: ':memory:'
        bq:
          type: bigquery
          path: 'project=project'
          read_only: true

This generates

FORCE INSTALL 'bigquery' FROM community;

I think this event supports local repositories, but they might need double quotes or something in the yaml config, so you can get to something like (note the quotes!)

INSTALL 'something-local' FROM 'https://some-other-repo';

Basically, blame @Kayrnt for setting me on this path.