feature[ats_ATS119815]: Switch group dialogs to use filtered tree

Change-Id: I590dd9a721ff9f4dd7f2765d6d1fd086ac9ec75c
feature[ats_ATS121337]: Add server call to count clients

Change-Id: Idea0a17b1b289a29fa5e4bcc4c8f36df4de270f7