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
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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