Kafo

Based on a discussion in https://github.com/theforeman/forklift/pull/1430#discussion_r739191912.

If a class (let's say puppet) is disabled, you can pass

--puppet-server true

but that's silently ignored. You need to explicitly pass

--enable-puppet --puppet-server true

to get the option to be recognized and passed to the Puppet.

The alternative is to silently enable the class but this may surprise a user. An explicit error allows users to understand they're enable additional functionality.