Greatly increase reliability of deferred closing

It's pretty hard to find a solution that checks all of the boxes. I want
something that:

- Closes instantly when you close the editor, and in REAPER you should
  be able to instantly switch between docked and floating modes
- Where there should not be a delay in user interaction when quickly
  reopening the editor (or doing that switching thing in REAPER since that's
  the same thing)
- Where the window manager should not try to reparent the window during
  the losing process as that can cause some jarring flickering
- And, of course, there should be no weird Wine X11Drv crashes

And it should do all of that in Bitwig, REAPER, Carla, Ardour and
Renoise. Apparently it's quite the task to find an approach that checks
all the boxes there.

src/wine-host/bridges/vst3.cpp

@@ -621,7 +621,8 @@ void Vst3Bridge::run() {
                         set_realtime_priority(false);
                         Editor& editor_instance =
                             object_instances[request.owner_instance_id]
-                                .editor.emplace(config, x11_handle);
+                                .editor.emplace(main_context, config,
+                                                x11_handle);
                         const tresult result =
                             object_instances[request.owner_instance_id]
                                 .plug_view_instance->plug_view->attached(