Hoping this prevents panics we were observing when starting.

Fixes this panic that I've been seeing in Slack:


[example](https://zed-industries.slack.com/archives/C04S6T1T7TQ/p1696530575535779)


```
thread 'main' panicked at 'assertion failed: opened_items.len() == project_paths_to_open.len()'
crates/workspace/src/workspace.rs:3628
<backtrace::capture::Backtrace>::create
<backtrace::capture::Backtrace>::new
Zed::init_panic_hook::{closure#0}
std::panicking::rust_panic_with_hook
std::panicking::begin_panic_handler::{{closure}}
std::sys_common::backtrace::__rust_end_short_backtrace
_rust_begin_unwind
core::panicking::panic_fmt
core::panicking::panic
<workspace::Workspace>::new_local::{closure#0}::{closure#0}
```

I believe it was caused by a window being closed immediately, while it
was still loading some paths. There was a mismatch in expectation
between the `workspace::open_items` function (which contains this
assertion), and the `Workspace::load_workspace` method. That later
method can return an empty vector if the workspace handle is dropped
while it is executing.

Release Notes:

- Fixed a crash when closing a Zed window immediately after opening it

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.

Refactored a bit how url arguments are handled to avoid adding too much
extra complexity to main.

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