Instead, %bundle and %add if we don't have the group locally yet,
or %add and %remove whatever the difference is between the local group
and the group as specified in the %path update.
In both, we make clear that the wire is always of the /@/group/^ form,
and alias the "group path" portion of the wire for clarity.
For kick, more obviously reuse the same wire, don't reconstruct it.
For watch-nack, only delete from the synced map if the source of the
watch-nack is still relevant. While we don't expect this to be relevant
considering current mode of operation, this does protect us against
strange cases.
Instead of providing a (unit path), allows for (list path), which better
supports the "update to path and subpath cases".
For example, if /things wants updates about everything, and
/things/specific wants updates about the specific thing, they'll both
need to receive a %fact when the specific thing changes.
Previously, these would have been two separate moves. Now, gall handles
the multi-targeting for you.
