add clusterId to json output of "cluster list", "cluster describe" commands
currently there is no straightforward way to get clusterId using mongocli. we can get clusterId if we use text format with "cluster list", but not with json.
and with json format we have to use "process list" command, filter out only one process amongst multiple within cluster and filter out clusterId.
it would be useful to add clusterId field into json when we get cluster description from list/describe commands also.