js: Queue 'later' via MetaLaters

This replaces the meta_later_add() API which used now removed global
singletons under the hood.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2557>

js/ui/status/system.js

@@ -107,7 +107,8 @@ class ScreenshotItem extends QuickSettingsItem {
 
         this.connect('clicked', () => {
             const topMenu = Main.panel.statusArea.quickSettings.menu;
-            Meta.later_add(Meta.LaterType.BEFORE_REDRAW, () => {
+            const laters = global.compositor.get_laters();
+            laters.add(Meta.LaterType.BEFORE_REDRAW, () => {
                 Main.screenshotUI.open().catch(logError);
                 return GLib.SOURCE_REMOVE;
             });