Refs #15779 - make background processing unavailable for now (#4217)

The original PR got vetted in the packaging phase and including
foreman-task as dependency of Foreman was refused. We need to rethink
our approach for getting the foreman-tasks functionality available...

Refs #17653 - fix typo in show_hidden_parameters and add tests

Fixes #6502 - List ignored classes and environments on import

When importing environments and classes from puppet, ignored
environments and classes defined in ignored_environments.yml
aren't aparent.

This will add them to the list to import as ignored and...

Fixes #17653 - Allow all parameters api to unhide values

Fixes #6952 - Set hostgroup after provisioning from pxe

After hostgroup provisioning, when the machine has registered
with foreman, it should be in the same hostgroup.
to achieve this behavier, the fact foreman_hostgroup should be
added to hostgroup provisioning template

Fixes #13775 - merge if data set is present

Fixes #17525 - Add a friendly error message to invalid dns_id

Fixes #17257 - Allow specific configs to be recreated

Fixes #17503 - Only trigger PXELoader suggestion when needed

Previously every host instantiation triggered a PXELoader suggestion,
which led to up to 3 extra queries per host loaded. This changes so that
the suggestion is only applied when a host changes it's OS.

Fixes #17548 - Orphaned smart class parameters are hidden