Require client ID 

As an admin, I find it easier to find clients interacting with the cluster when there is a client ID associated with them? 

Anything against requiring that as a parameter? Perhaps even defaulting to the one kafka would make anyway? 

Ref https://github.com/wix/greyhound/blob/master/core/src/main/scala/com/wixpress/dst/greyhound/core/admin/AdminClient.scala#L79 