onPeerUnresponsive
Opens (or refreshes) the reconnect window for peerId.
Called by the leader when a peer's link drops. Emits JoinerReconnectEvent.WindowOpened on events.
When a PartitionEvent.PeerUnresponsive feed is available, bridge it here: partitionEvents.collect { if (it is PeerUnresponsive) onPeerUnresponsive(it.peerId, it.at) }.