Add multi-database support

[ywelsch]

DuckDB has support for attaching multiple databases. The catalog UI currently only takes the default DB into account. It would be great to show all databases/catalogs and their schemas on the left hand side, with the current default database highlighted.

[tconbeer]

Seems that the docs are wrong, and table_catalog is implemented in information_schema.tables and information_schema.columns, so this should be a very easy add.

[ywelsch]

A minor gotcha is that the catalog view information_schema.schemata is still needed for catalogs/DBs that do not have tables yet. current_database() / current_catalog() can be used to identify the current DB.

[tconbeer]

@ywelsch This has been released in 0.0.14. Thanks for your issue! You can also now open multple databases right from the command line:

harlequin f1.db iris.db

[ywelsch]

Awesome! I've tried it out, works perfectly. Thank you.