SYSTEMD: Re-read KCM configuration on systemctl restart kcm
    
    Related:
    https://pagure.io/SSSD/sssd/issue/3862
    
    Uses the sssd command together with the --genconf-section=kcm option to
    refresh the kcm configuration when the sssd-kcm systemd service is
    restarted.
    
    This allows the administrator to e.g. just drop a snippet to
    /etc/sssd.conf.d/ or create the [kcm] section directly in the main sssd
    config file, then just restart the sssd-kcm service for the changes to
    apply.
    
    Reviewed-by: Michal Židek <mzidek@redhat.com>