Move "async move" a few characters to the left in cx.spawn() (#26758)

This is the core change:
https://github.com/zed-industries/zed/pull/26758/files#diff-044302c0d57147af17e68a0009fee3e8dcdfb4f32c27a915e70cfa80e987f765R1052

TODO:
- [x] Use AsyncFn instead of Fn() -> Future in GPUI spawn methods
- [x] Implement it in the whole app
- [x] Implement it in the debugger 
- [x] Glance at the RPC crate, and see if those box future methods can
be switched over. Answer: It can't directly, as you can't make an
AsyncFn* into a trait object. There's ways around that, but they're all
more complex than just keeping the code as is.
- [ ] Fix platform specific code

Release Notes:

- N/A

crates/recent_projects/src/ssh_connections.rs

@@ -455,13 +455,13 @@ impl remote::SshClientDelegate for SshClientDelegate {
         version: Option<SemanticVersion>,
         cx: &mut AsyncApp,
     ) -> Task<anyhow::Result<PathBuf>> {
-        cx.spawn(|mut cx| async move {
+        cx.spawn(async move |cx| {
             let binary_path = AutoUpdater::download_remote_server_release(
                 platform.os,
                 platform.arch,
                 release_channel,
                 version,
-                &mut cx,
+                cx,
             )
             .await
             .map_err(|e| {
@@ -486,13 +486,13 @@ impl remote::SshClientDelegate for SshClientDelegate {
         version: Option<SemanticVersion>,
         cx: &mut AsyncApp,
     ) -> Task<Result<Option<(String, String)>>> {
-        cx.spawn(|mut cx| async move {
+        cx.spawn(async move |cx| {
             AutoUpdater::get_remote_server_release_url(
                 platform.os,
                 platform.arch,
                 release_channel,
                 version,
-                &mut cx,
+                cx,
             )
             .await
         })