coordination: enhance GroupAlreadyExist exception

Change-Id: Iff02e1d1562ed01672a82327e8a06baa9fce1183
coordination: enhance MemberNotJoined

Change-Id: I51d599abee283ff8ba29ad68f157218966ac6ead
coordination: enhance GroupNotCreated exception

Change-Id: I98194d4c236faa9005324b3d70cd97d1a732cdda
coordination: enhance MemberAlreadyExist exception

Change-Id: I1c3c56e405d7cce2edfdedfe4e129c9c366a5afe