List threads over a channel / event bus

[sanderpick]

Currently, listing threads requires building a list of objects that contain data catted from the local repo. If for some reason some of that data is not available, we have to request it from the network which can hang the listing process which sucks for the end user. They should be able to see other threads ASAP.

The proposal is to deliver expanded threads over a channel that can be consumed by the cli / mobile event bus.

I'm not sure why the needed thread nodes sometimes appear to be not pinned locally, which results in this behavior - we should further investigate this after landing threads v2 - perhaps this event fix won't be needed.