windowManager: Handle starting/stopping of X11 services

We now do 2 things along Xwayland startup/shutdown:
- Start or stop the gnome-session-x11-services target, that will
  pull all X11 related services that the session might depend on.
- As we start ibus-daemon manually, trigger a restart in order to
  toggle the XIM daemon on and off along with Xwayland presence.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/680

js/misc/ibusManager.js

@@ -61,7 +61,7 @@ var IBusManager = class {
 
     _spawn(extraArgs = []) {
         try {
-            let cmdLine = ['ibus-daemon', '--panel', 'disable', '--xim', ...extraArgs];
+            let cmdLine = ['ibus-daemon', '--panel', 'disable', ...extraArgs];
             Gio.Subprocess.new(cmdLine, Gio.SubprocessFlags.NONE);
         } catch (e) {
             log(`Failed to launch ibus-daemon: ${e.message}`);