This fixes some bugs in our following logic, due to our attempts to
prevent infinite loops when two people follow each other.

* Propagate all of leader's views to a new follower, even if those views
were originally created by that follower.
* Propagate active view changes to followers, even if the active view is
following that follower.
* Avoid redundant active view updates on the client.

Release Notes:

- Fixed bugs where it was impossible to follow someone into a view that
they previously following you into.

TODO:
- [x] Add markdown rendering to channel chat
- [x] Unify (?) rendering logic between hover popover and chat
- [x] ~~Determine how to deal with document-oriented markdown like `#`~~
Unimportant until we want to do something special with `#channel`
- [x] Tidy up spacing and styles in chat panel

Release Notes:

- Added markdown rendering to channel chat
- Improved channel chat message style
- Fixed a bug where long chat messages would not soft wrap

* Propagate all of leader's views to a new follower, even if those views
  were originally created by that follower.
* Propagate active view changes to followers, even if the active view is
  following that follower.
* Avoid redundant active view updates on the client.

Release Notes:

- N/A

Release Notes:

- `up` and `down` now go to the correct place after inserting

Release Notes:

- Fix clicking the notes icon when people are in the channel (preview
only)

Release Notes:

- Add user avatars to channel chat messages
- Group messages by sender
- Fix visual bugs in new chat and note buttons

Also, remove logic for implicitly marking chat messages as observed when
they are fetched. I think this is unnecessary, because the client always
explicitly acknowledges messages when they are shown.

Release Notes:

- Fixed a bug where chat messages were shown out of order (preview only)

co-authored-by: conrad <conrad.irwin@gmail.com>

Release Notes:

- Fixes a panic in vim when incrementing a non-number.

- use SaveAll instead of Save
- TODO: fix where closing a multi-buffer gives a confusing save prompt

Release Notes:

- Fix bugs arising from saving an untitled buffer

Co-Authored-By: Mikayla Maki <mikayla@zed.dev>

This PR adds a mechanism for notifying the client when a channel note
has been edited or a message has been changed.

TODO: 
- [x] Fix infinite loop when opening the chat panel
- [x] Switch to client-side ack model of observation detection
- [x] Add client-side-only change detection (e.g. for when a channel
note is open locally but not focused)
- [x] Review implementation / query performance.
- [x] Fix lack of ACK on restart for channel buffers
- [x] remove channel note opening on click
- [x] Fix channel messages sent while chat channel is in the background
not showing the channel as changed.

Release Notes:

- N/A

co-authored-by: max <max@zed.dev>

Co-authored-by: conrad <conrad.irwin@gmail.com>
Co-authored-by: max <max@zed.dev>

co-authored-by: Conrad <conrad.irwin@gmail.com>

co-authored-by: conrad <conrad.irwin@gmail.com>

co-authored-by: conrad <conrad.irwin@gmail.com>

Co-authored-by: Mikayla <mikayla@zed.dev>

Co-authored-by: Mikayla <mikayla@zed.dev>

Release Notes:

- Clicking on a channel in the sidebar will now join the channel and
open the notes
- If you join a channel that already shared projects, you will join the
projects automatically and follow the host.
- Clicking on the current channel in the sidebar will re-open the notes.
- Chat can now be accessed from the right click menu of channels.


- (probably not worth mentioning) Various improvements to hover states
and tooltips in the collab ui; and if you click on a channel while in
another call, confirm before switching.

co-authored-by: Max <max@zed.dev>

Co-authored-by: Max <max@zed.dev>

Release Notes:

- N/A

Co-Authored-By: Julia <30666851+ForLoveOfCats@users.noreply.github.com>

Reverts zed-industries/zed#3049