Ryujinx.Ava: fixes for random hangs on exit (#4827)

* Attempt at fixing hang on exit by ending the WindowNotificationManager notification loop, so that the Thread running it can exit.

* explicitly apply the NotificationManager template to allow the notification loop to begin

* NotificationHelper - remove explicity call to ApplyTemplate(). Change to ManualResetEventSlim so we can cancel the Wait on it.

* add a timeout to AudioRenderSystem.Stop()'s waiting for the termination signal, log a warning if this timeout occurs, and continue execution

* NotifiationHelper - cancel first, the CompleteAdding()

* Remove AudioRenderSystem._terminationEvent, redundant

* NotificationHelper - use host.Closing event to trigger cancellation instead of _notifationManager.DetachedFromLogicalTree

* Change NotificationHelper to use an explicit Thread for background work.  Wait on the cancellationToken's WaitHandle so the Thread doesn't have to deal with async. Wrap foreach in try/catch (OperationCanceledException) to swallow the escaping exception from the GetConsumingEnumerable().

* adjust formatting of AsyncWorkQueue constructor to use object initializers consistently

* use AsyncWorkQueue to do everything I added in SetNotificationManager()

* Revert "use AsyncWorkQueue to do everything I added in SetNotificationManager()"

This reverts commit f0e78366b8776ec8e2fef8ab023c0db1833155d3.

* use AsyncWorkQueue to handle the Thread-related changes previously made to NotificationHelper.SetNotificationHelper(). Wrap it in Lazy<T> and force instantiation in the TemplateApplied event handler to accomodate for the fact that AsyncWorkQueue starts immediately, and the notification dispatch loop was being delayed by _templateAppliedEvent.

* impl changes suggested by AcK77

* impl changes suggested by AcK77 (more)

src/Ryujinx.Common/AsyncWorkQueue.cs

@@ -22,9 +22,11 @@ namespace Ryujinx.Common
             _cts = new CancellationTokenSource();
             _queue = collection;
             _workerAction = callback;
-            _workerThread = new Thread(DoWork) { Name = name };
-
-            _workerThread.IsBackground = true;
+            _workerThread = new Thread(DoWork)
+            {
+                Name = name,
+                IsBackground = true
+            };
             _workerThread.Start();
         }