Single upgrade rake task
Currently there are many rake tasks for upgrades that are called one-by-one in the installer. This means that for every upgrade step we need to write code for an additional task. I'd be much easier if there was a single task that wrapped all katello:upgrades:* tasks so we could simply do foreman-rake katello:upgrade.
Fixes #21938 - add plugable upgrade rake task
This commit adds the ability for upgrade rake tasks to be defined
within seeds. The installer can then run the upgrade:run rake task
to run them. Tasks can be defined to run once or to always run when
the upgrade:run master task is run.