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/assistant_tools/src/bash_tool.rs

@@ -50,7 +50,7 @@ impl Tool for BashTool {
         };
         let working_directory = worktree.read(cx).abs_path();
 
-        cx.spawn(|_| async move {
+        cx.spawn(async move |_| {
             // Add 2>&1 to merge stderr into stdout for proper interleaving.
             let command = format!("({}) 2>&1", input.command);
 

crates/assistant_tools/src/diagnostics_tool.rs

@@ -65,10 +65,10 @@ impl Tool for DiagnosticsTool {
             };
             let buffer = project.update(cx, |project, cx| project.open_buffer(project_path, cx));
 
-            cx.spawn(|cx| async move {
+            cx.spawn(async move |cx| {
                 let mut output = String::new();
                 let buffer = buffer.await?;
-                let snapshot = buffer.read_with(&cx, |buffer, _cx| buffer.snapshot())?;
+                let snapshot = buffer.read_with(cx, |buffer, _cx| buffer.snapshot())?;
 
                 for (_, group) in snapshot.diagnostic_groups(None) {
                     let entry = &group.entries[group.primary_ix];

crates/assistant_tools/src/edit_files_tool.rs

@@ -103,7 +103,7 @@ impl Tool for EditFilesTool {
                     cx,
                 );
 
-                cx.spawn(|mut cx| async move {
+                cx.spawn(async move |cx| {
                     let result = task.await;
 
                     let str_result = match &result {
@@ -111,10 +111,8 @@ impl Tool for EditFilesTool {
                         Err(err) => Err(err.to_string()),
                     };
 
-                    log.update(&mut cx, |log, cx| {
-                        log.set_tool_output(req_id, str_result, cx)
-                    })
-                    .log_err();
+                    log.update(cx, |log, cx| log.set_tool_output(req_id, str_result, cx))
+                        .log_err();
 
                     result
                 })
@@ -188,7 +186,7 @@ impl EditToolRequest {
             cache: false,
         });
 
-        cx.spawn(|mut cx| async move {
+        cx.spawn(async move |cx| {
             let llm_request = LanguageModelRequest {
                 messages,
                 tools: vec![],
@@ -211,10 +209,10 @@ impl EditToolRequest {
             };
 
             while let Some(chunk) = chunks.stream.next().await {
-                request.process_response_chunk(&chunk?, &mut cx).await?;
+                request.process_response_chunk(&chunk?, cx).await?;
             }
 
-            request.finalize(&mut cx).await
+            request.finalize(cx).await
         })
     }
 

crates/assistant_tools/src/read_file_tool.rs

@@ -70,14 +70,14 @@ impl Tool for ReadFileTool {
             return Task::ready(Err(anyhow!("Path not found in project")));
         };
 
-        cx.spawn(|mut cx| async move {
+        cx.spawn(async move |cx| {
             let buffer = cx
                 .update(|cx| {
                     project.update(cx, |project, cx| project.open_buffer(project_path, cx))
                 })?
                 .await?;
 
-            let result = buffer.read_with(&cx, |buffer, _cx| {
+            let result = buffer.read_with(cx, |buffer, _cx| {
                 if buffer
                     .file()
                     .map_or(false, |file| file.disk_state().exists())
@@ -102,7 +102,7 @@ impl Tool for ReadFileTool {
                 }
             })??;
 
-            action_log.update(&mut cx, |log, cx| {
+            action_log.update(cx, |log, cx| {
                 log.buffer_read(buffer, cx);
             })?;
 

crates/assistant_tools/src/regex_search_tool.rs

@@ -73,7 +73,7 @@ impl Tool for RegexSearchTool {
 
         let results = project.update(cx, |project, cx| project.search(query, cx));
 
-        cx.spawn(|cx| async move {
+        cx.spawn(async move|cx|  {
             futures::pin_mut!(results);
 
             let mut output = String::new();
@@ -86,7 +86,7 @@ impl Tool for RegexSearchTool {
                     continue;
                 }
 
-                buffer.read_with(&cx, |buffer, cx| -> Result<(), anyhow::Error> {
+                buffer.read_with(cx, |buffer, cx| -> Result<(), anyhow::Error> {
                     if let Some(path) = buffer.file().map(|file| file.full_path(cx)) {
                         let mut file_header_written = false;
                         let mut ranges = ranges