Add the ability to edit remote directories over SSH (#14530)

This is a first step towards allowing you to edit remote projects
directly over SSH. We'll start with a pretty bare-bones feature set, and
incrementally add further features.

### Todo

Distribution
* [x] Build nightly releases of `zed-remote-server` binaries
    * [x] linux (arm + x86)
    * [x] mac (arm + x86)
* [x] Build stable + preview releases of `zed-remote-server`
* [x] download and cache remote server binaries as needed when opening
ssh project
* [x] ensure server has the latest version of the binary


Auth
* [x] allow specifying password at the command line
* [x] auth via ssh keys
* [x] UI password prompt

Features
* [x] upload remote server binary to server automatically
* [x] opening directories
* [x] tracking file system updates
* [x] opening, editing, saving buffers
* [ ] file operations (rename, delete, create)
* [ ] git diffs
* [ ] project search

Release Notes:

- N/A

---------

Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>

crates/multi_buffer/src/multi_buffer.rs

@@ -4807,7 +4807,7 @@ mod tests {
     fn test_remote(cx: &mut AppContext) {
         let host_buffer = cx.new_model(|cx| Buffer::local("a", cx));
         let guest_buffer = cx.new_model(|cx| {
-            let state = host_buffer.read(cx).to_proto();
+            let state = host_buffer.read(cx).to_proto(cx);
             let ops = cx
                 .background_executor()
                 .block(host_buffer.read(cx).serialize_ops(None, cx));