This change makes it so that if you are the first to join a channel,
your project is automatically shared.
It also makes it so that if you join a channel via a link and there are
no shared projects, you open the notes instead of an empty workspace
with nothing.
This is to try and address the discoverability of project sharing: we've
had
two reviews that have talked about channels, but not talked about
sharing
projects into them, which makes me suspect they didn't know about the
feature.
Release Notes:
- Added a setting `share_on_join` (defaulting to true). When set, and
you join an empty channel, your project is automatically shared.
