No insistence on unit_entry ever or service_entry with absent manage_unit

[traylenator]

Pull Request (PR) description

Removing a unit file with systemd::manage_unit with the following:

systemd::manage_unit {'foo.service':
  ensure     => 'absent',
}

This is not possible and a service_entry and unit_entry must be specified as the unit name
is in the service namespace.

Remove insistence for unit_entry and service_name parameter for the absent case.

For the ensure => 'present`` the unit_entryis no longer required since it is perfectly possible to create units without any[Unit]` section.

Also improve failure message when service_entry is not specified for service unit.

[Geod24]

Should we require a unit_entry as well ? All fields in types are optional, and you can have a systemd unit file without a [Unit] entry (e.g. for timers).

[traylenator]

Should we require a unit_entry as well ? All fields in types are optional, and you can have a systemd unit file without a [Unit] entry (e.g. for timers).

Agreed:

# cat test.timer  && systemd-analyze verify test.timer && echo 'good'

[Timer]
OnBootSec=10min
OnUnitInactiveSec=1w
Unit=dnf-clean.service

good

I'll make the change.

[traylenator]

systemd::manage_unit {'foo.service':
ensure => 'absent',
}

So both:

systemd::manage_unit {'foo.service':
  ensure     => 'absent',
}

and

systemd::manage_unit {'foo.service':
  ensure     => 'present',
  service_entry => {
     ....
  },
}

are now both valid.

[smortex]

LGTM