Configuration option to skip migrations on secondary databses

Hello

I have started to connect with legacy databases using rails 6 pattern and I’m in trouble dealing with migrations since then.

I feel that was great to have a configuration option to skip_migration: true. These could be useful to read-only like connections.

Is this a good idea or I just should establish_connection without using database configuration file? Thanks for your feed back.

I can add a PR in case this is a possibility.