shellDBus: Add AcceleratorDeactivated D-Bus signal

Add this signal to complement AcceleratorActivated, meant to happen
on the release action of shortcuts, e.g. on push-to-talk.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3598>

js/ui/shellDBus.js

@@ -37,6 +37,10 @@ export class GnomeShell {
             (display, action, device, timestamp) => {
                 this._emitAcceleratorActivated(action, device, timestamp);
             });
+        global.display.connect('accelerator-deactivated',
+            (display, action, device, timestamp) => {
+                this._emitAcceleratorDeactivated(action, device, timestamp);
+            });
 
         this._cachedOverviewVisible = false;
         Main.overview.connect('showing',