Rebuild SSH installation (#20220)

Closes #ISSUE

This refactors SSH installation to require less shell stuff. We'd like
to
support arbitrary remote hosts, and unfortunately csh/tcsh have quoting
rules
that make it impossible to run multi-line scripts.

The primary changes are:
* The target path now contains the version:
`./zed_server/zed-remote-server-{release_channel}-{version}`
* We do all our processing in a temporary file and `mv` it into place.
* We do fewer calls to `ssh_command` overall. With the previous two
changes we can avoid lock files, and fuser calls. Instead cleanup of old
binaries now happens in `execute_run`.
* We only try to install the remote server when the connection is
established, not on each project open.

This should also put us in a good position if we want to pre-emptively
install new versions when the auto-updater detects an update for the
running version of zed (but that's not wired up yet)

Release Notes:

- Remoting: Fixed remoting when the remote runs `tcsh`
- Remoting: Improved latency of connecting

crates/auto_update/src/auto_update.rs

@@ -432,6 +432,9 @@ impl AutoUpdater {
         cx.notify();
     }
 
+    // If you are packaging Zed and need to override the place it downloads SSH remotes from,
+    // you can override this function. You should also update get_remote_server_release_url to return
+    // Ok(None).
     pub async fn download_remote_server_release(
         os: &str,
         arch: &str,
@@ -482,7 +485,7 @@ impl AutoUpdater {
         release_channel: ReleaseChannel,
         version: Option<SemanticVersion>,
         cx: &mut AsyncAppContext,
-    ) -> Result<(JsonRelease, String)> {
+    ) -> Result<Option<(String, String)>> {
         let this = cx.update(|cx| {
             cx.default_global::<GlobalAutoUpdate>()
                 .0
@@ -504,7 +507,7 @@ impl AutoUpdater {
         let update_request_body = build_remote_server_update_request_body(cx)?;
         let body = serde_json::to_string(&update_request_body)?;
 
-        Ok((release, body))
+        Ok(Some((release.url, body)))
     }
 
     async fn get_release(