Foreman Maintain

Fixes #20870 - hammer ping check with default tag

Fixes #19715 - [Check] WARN if foreman-proxy is self-registered

Fixes #20847 - Unify steps description

Merge remote-tracking branch 'origin/master' into upgrade-workflow

Fixes #46 - isc dhcp configuration check

Configure repositories and update packages

Move sync-plans checks to pre/post migrations

Full upgrade scenario

This commit intoroduces more structured upgrade scenario consisting of
this scenarios:

• pre_upgrade_check - non-modifying checks: is the system ready?
• pre_migrations - modifying procedures before source update
• migrations - source update and main migrations...

Retain original objects while Tsorting. TSort create label graph and then convert to object graph

Define order using ruby TSort

1. Introduce 2 metadata: 'before' and 'after'
2. Current order is:
Checks::SyncPlans::WithEnabledStatus
Checks::DiskSpeedMinimal
Checks::SystemRegistration
Checks::ForemanTasks::NotPaused
Checks::ForemanTasks::NotRunning
Checks::ForemanTasks::Invalid::CheckOld...