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/inline_completion_button/src/inline_completion_button.rs

@@ -604,11 +604,11 @@ impl InlineCompletionButton {
                     if let Some(workspace) = window.root().flatten() {
                         let workspace = workspace.downgrade();
                         window
-                            .spawn(cx, |cx| {
+                            .spawn(cx, async |cx| {
                                 open_disabled_globs_setting_in_editor(
                                     workspace,
                                     cx,
-                                )
+                                ).await
                             })
                             .detach_and_log_err(cx);
                     }
@@ -768,10 +768,10 @@ impl SupermavenButtonStatus {
 
 async fn open_disabled_globs_setting_in_editor(
     workspace: WeakEntity<Workspace>,
-    mut cx: AsyncWindowContext,
+    cx: &mut AsyncWindowContext,
 ) -> Result<()> {
     let settings_editor = workspace
-        .update_in(&mut cx, |_, window, cx| {
+        .update_in(cx, |_, window, cx| {
             create_and_open_local_file(paths::settings_file(), window, cx, || {
                 settings::initial_user_settings_content().as_ref().into()
             })
@@ -782,7 +782,7 @@ async fn open_disabled_globs_setting_in_editor(
 
     settings_editor
         .downgrade()
-        .update_in(&mut cx, |item, window, cx| {
+        .update_in(cx, |item, window, cx| {
             let text = item.buffer().read(cx).snapshot(cx).text();
 
             let settings = cx.global::<SettingsStore>();