Implement 'adcli testjoin'
By calling adcli testjoin it will be checked if the host credentials stored in the keytab are still valid.
Related to https://bugzilla.redhat.com/show_bug.cgi?id=1622583
By calling adcli testjoin it will be checked if the host credentials stored in the keytab are still valid.
Related to https://bugzilla.redhat.com/show_bug.cgi?id=1622583