add NotificationService, cleanup

MareSynchronos/Mediator/MediatorSubscriberBase.cs

@@ -0,0 +1,16 @@
+namespace MareSynchronos.Mediator;
+
+public abstract class MediatorSubscriberBase : IDisposable
+{
+    protected MediatorSubscriberBase(MareMediator mediator)
+    {
+        Mediator = mediator;
+    }
+
+    protected readonly MareMediator Mediator;
+
+    public virtual void Dispose()
+    {
+        Mediator.UnsubscribeAll(this);
+    }
+}