worklist 19807: Fixed bug in OctreeEditPacketSender where there was one outgoing seq number for all nodes.

Issue: OctreeEditPacketSender had one outgoing sequence number being shared across all nodes, which means edit packets could be sent like so:
seq 0 to node A
seq 1 to node A
seq 2 to node B
seq 3 to node A

Fix: The sequence number was replaced by a map of sequence numbers, one for each active node.

Test: Ran local ACs and verified that each node received the correct stream of sequence numbers.