config-check: Message when sssd.conf is missing
sssctl config-check should print a message for user
if no sssd.conf was found.
Resolves:
https://pagure.io/SSSD/sssd/issue/3330
Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>
Reviewed-by: Petr Čech <pcech@redhat.com>
Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>