link-listen-hook: recover neglected collections
link-listen-hook: recover neglected collections

During the #2607 upgrade, strictly local collections got left out of the
listening set. (Because they did not have any outgoing subscriptions.)
This led to personal collections not being available on the frontend.

Here, we add upgrade logic for adding those back to our listening set again.
If a user had explicitly left a personal collection (instead of deleted it, for
whatever reason), they will have to leave it again. This case seems much more
rare than the "my collection is gone" one.
urbit/urbit,jfranklin9000/urbit,urbit/urbit,urbit/urbit,ngzax/urbit,urbit/urbit,ngzax/urbit,jfranklin9000/urbit,ngzax/urbit,jfranklin9000/urbit,ngzax/urbit,urbit/urbit,urbit/urbit,jfranklin9000/urbit,jfranklin9000/urbit,jfranklin9000/urbit,ngzax/urbit,ngzax/urbit,jfranklin9000/urbit,urbit/urbit,ngzax/urbit