Fixes #37471 - Support Zeitwerk loader

[ofedoren]

WIP

What are the changes introduced in this pull request?

This PR should make Katello plugin compatible with Zeitwerk autoloader, which will be enabled in Foreman instead of classic Rails' loader.

Considerations taken when implementing this change?

I was trying to change rather less than more. Although, some stuff (like CV acronym) can be introduced, but will require more changes and I'm not sure it'll be quite safe. It's up to maintainers.

What are the testing steps for this pull request?

Test with Foreman main PR (included in CI workflow) and hope for the best. Note: at first it'll be red, since some plugins, which are dependencies, should be updated as well. Additionally, after the tests are green I strongly recommend to test out basic/advanced content related workflows live.

[jeremylenz]

I had to check out:

• Fixes #37453 - Support Zeitwerk loader theforeman/foreman_remote_execution#895
• Fixes #37452 - Support Zeitwerk loader theforeman/foreman-tasks#752
• Fixes #29991 - Enable Zeitwerk theforeman/foreman#10131

I tested

• refreshing my manifest
• deleting a subscription from my manifest
• enabling a RH repository
• disabling a RH repository
• publish and promote a CV
• remove a package from a custom repository
• create new blank docker repo
• syncing all repos

Seems all good so far! I grepped development.log for zeitwerk and "uninitialized constant" and didn't see anything concerning.

[jeremylenz]

also notable: With the foreman-tasks PR checked out, I did not see this error

Zeitwerk::NameError: expected file /home/runner/work/katello/katello/vendor/bundle/ruby/2.7.0/gems/foreman-tasks-9.1.1/app/lib/actions/middleware/keep_current_request_id.rb to define constant Actions::Middleware::KeepCurrentRequestId, but didn't

which is currently failing in CI.