ipatests: add get_kdcinfo
get_kdcinfo(host) retrieves /var/lib/sss/pubconf/kdcinfo.$REALM on host.
It also logs whether SSSD considers the IPA domain as Online or not before
and after retrieving the file.
Related: https://pagure.io/freeipa/issue/8510
Signed-off-by: François Cami <fcami@redhat.com>
Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>