Moved all PInvokes to a lower class without any relianceon WPF, NotificationIconHelper, TaskbarHelper, SystemPersonalisationHelper are WPF window no more

src/NotificationFlyout.Shared.UI/WndProc/WndProcHandlerSubscriber.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Linq;
+
+namespace NotificationFlyout.Shared.UI.Helpers
+{
+    public class WndProcHandlerSubscriber : IWndProcHandlerSubscriber
+    {
+        private static readonly Lazy<WndProcHandlerSubscriber> _current = new(() => new WndProcHandlerSubscriber());
+        public static WndProcHandlerSubscriber Current => _current.Value;
+
+        public void Subscribe<TWndProcHandler>(TWndProcHandler handler) where TWndProcHandler : IWndProcHandler
+        {
+            var handlers = WndProcHandlerCollection.Current;
+            lock (handlers)
+            {
+                if (handlers.Any(x => x.Matches(handler))) return;
+                handlers.Add(new WndProcHandlerReference(handler));
+            }
+        }
+    }
+}