runDialog: Use new app based launch helper

Doing this has the advantage of using the GLib GDesktopAppInfo launching
API, resulting in the automatic registration of the application with
systemd.

See: https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1596
Closes: #3025

https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1384

js/ui/runDialog.js

@@ -196,7 +196,7 @@ class RunDialog extends ModalDialog.ModalDialog {
                     let execArg = this._terminalSettings.get_string(EXEC_ARG_KEY);
                     command = '%s %s %s'.format(exec, execArg, input);
                 }
-                Util.trySpawnCommandLine(command);
+                Util.trySpawnAppCommandline(command);
             } catch (e) {
                 // Mmmh, that failed - see if @input matches an existing file
                 let path = null;