Foreman Maintain

This will introduce more structured upgrade scenario consisting of below scenarios:

• pre_upgrade_check - non-modifying checks: is the system ready?
• pre_migrations - modifying procedures before source update
• migrations - source update and main migrations
• post_migrations - additional steps after migration
• post_upgrade_check - non-modifying checks: was the upgrade successful

If there were some failures or warnings in the checks, the reporter
informs the user about it and asks for confirmation.

Also, included below things:

• --whitelist option
• full upgrade experience: move some checks to pre/post migrations + add setting of repositories, yum update and installer run