Combined refactoring and attributes interface

I can split this up, but for now it is easier to have it all in one place.
Also we can pick or discard specific commits.

Currently the services refactoring in this MR is problematic.
See 📌 Refactoring hux services breaks container rebuild Closed: cannot reproduce

It would be nice if modules could provide invariants that, if changed, force a container rebuild in early bootstrap (Drupal kernel), before the module handler is created.

This would be something to add to Drupal core.

The problems mentioned above only occur with drush 12, not drush 11.
See my latest comments in 📌 Refactoring hux services breaks container rebuild Closed: cannot reproduce .

So, I removed the awkwards commits that try to avoid this problem.

Also added a test for custom attribute class.