On witnessing another node leaving a cluster, generate leave presence about all MUC participants from that node to all node-local MUC participants

Description

Like OF-2229.

Use the list from https://igniterealtime.atlassian.net/browse/OF-2224 to identify who has gone, and for all local active MUC participants, generate a leave presence for each of the now-unreachable participants.

Environment

None

Assignee

Guus der Kinderen

Reporter

Dan Caseley