idviews: Complain if host is already assigned the ID View in idview-apply

When running a idview-apply command, the hosts that were already assigned
the desired view were silently ignored. Make sure such hosts show up in
the list of failed hosts.

https://fedorahosted.org/freeipa/ticket/4743

Reviewed-By: Jan Cholasta <jcholast@redhat.com>
Reviewed-By: Petr Vobornik <pvoborni@redhat.com>
idviews: Ignore host or hostgroup options set to None

Since passing --hosts= or --hostsgroups= to idview-apply or unapply
commands does not make sense, ignore it.

https://fedorahosted.org/freeipa/ticket/4806

Reviewed-By: Petr Vobornik <pvoborni@redhat.com>