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/language_models/src/provider/ollama.rs

@@ -69,7 +69,7 @@ impl State {
         let api_url = settings.api_url.clone();
 
         // As a proxy for the server being "authenticated", we'll check if its up by fetching the models
-        cx.spawn(|this, mut cx| async move {
+        cx.spawn(async move |this, cx| {
             let models = get_models(http_client.as_ref(), &api_url, None).await?;
 
             let mut models: Vec<ollama::Model> = models
@@ -83,7 +83,7 @@ impl State {
 
             models.sort_by(|a, b| a.name.cmp(&b.name));
 
-            this.update(&mut cx, |this, cx| {
+            this.update(cx, |this, cx| {
                 this.available_models = models;
                 cx.notify();
             })
@@ -101,7 +101,7 @@ impl State {
         }
 
         let fetch_models_task = self.fetch_models(cx);
-        cx.spawn(|_this, _cx| async move { Ok(fetch_models_task.await?) })
+        cx.spawn(async move |_this, _cx| Ok(fetch_models_task.await?))
     }
 }
 
@@ -204,7 +204,7 @@ impl LanguageModelProvider for OllamaLanguageModelProvider {
         let http_client = self.http_client.clone();
         let api_url = settings.api_url.clone();
         let id = model.id().0.to_string();
-        cx.spawn(|_| async move { preload_model(http_client, &api_url, &id).await })
+        cx.spawn(async move |_| preload_model(http_client, &api_url, &id).await)
             .detach_and_log_err(cx);
     }
 
@@ -421,14 +421,14 @@ impl ConfigurationView {
     pub fn new(state: gpui::Entity<State>, window: &mut Window, cx: &mut Context<Self>) -> Self {
         let loading_models_task = Some(cx.spawn_in(window, {
             let state = state.clone();
-            |this, mut cx| async move {
+            async move |this, cx| {
                 if let Some(task) = state
-                    .update(&mut cx, |state, cx| state.authenticate(cx))
+                    .update(cx, |state, cx| state.authenticate(cx))
                     .log_err()
                 {
                     task.await.log_err();
                 }
-                this.update(&mut cx, |this, cx| {
+                this.update(cx, |this, cx| {
                     this.loading_models_task = None;
                     cx.notify();
                 })