Regenerate completion labels on resolve (#21521)

Closes https://github.com/zed-industries/zed/issues/21516

Technically, this is an LSP violation from `vtsls`, but seems that it's
not going to be fixed adequately on that side, see
https://github.com/yioneko/vtsls/issues/213 for more context.
So, we have to accommodate at least for now.

Release Notes:

- Fixed completion item labels not being updated after the resolve for
non-LSP compliant servers

crates/editor/src/editor.rs

@@ -1181,9 +1181,9 @@ impl CompletionsMenu {
         let delay = Duration::from_millis(delay_ms);
 
         completion_resolve.lock().fire_new(delay, cx, |_, cx| {
-            cx.spawn(move |this, mut cx| async move {
+            cx.spawn(move |editor, mut cx| async move {
                 if let Some(true) = resolve_task.await.log_err() {
-                    this.update(&mut cx, |_, cx| cx.notify()).ok();
+                    editor.update(&mut cx, |_, cx| cx.notify()).ok();
                 }
             })
         });