### Todo
* [x] Snapshot channel buffers when everyone closes the buffer
* [x] Ensure that users who are in both a project and a channel note
have the same color in both places
* [x] Allow following project collaborators into channel notes
* [x] Expose notes for the current channel under "Current Call" section
of the collaboration panel
* [x] Offline state for the channel notes view
* [x] Make the channel context menu accessible to all members (to expose
the notes)
* [x] Wire in view and Item method overrides
Release Notes:
- N/A
fbc7b37b2f