Use UpdateGlobal accessors in more places (#11925)

This PR updates a number of instances that were previously using
`cx.update_global` to use `UpdateGlobal::update_global` instead.

Release Notes:

- N/A

crates/zed/src/main.rs

@@ -943,7 +943,8 @@ fn watch_languages(_fs: Arc<dyn fs::Fs>, _languages: Arc<LanguageRegistry>, _cx:
 fn watch_file_types(fs: Arc<dyn fs::Fs>, cx: &mut AppContext) {
     use std::time::Duration;
 
-    use gpui::BorrowAppContext;
+    use file_icons::FileIcons;
+    use gpui::UpdateGlobal;
 
     let path = {
         let p = Path::new("assets/icons/file_icons/file_types.json");
@@ -957,7 +958,7 @@ fn watch_file_types(fs: Arc<dyn fs::Fs>, cx: &mut AppContext) {
         let mut events = fs.watch(path.as_path(), Duration::from_millis(100)).await;
         while (events.next().await).is_some() {
             cx.update(|cx| {
-                cx.update_global(|file_types, _| {
+                FileIcons::update_global(cx, |file_types, _cx| {
                     *file_types = file_icons::FileIcons::new(Assets);
                 });
             })