Restructure solution layout by module

src/Notify/StellaOps.Notify.Worker/Handlers/INotifyEventHandler.cs

@@ -0,0 +1,10 @@
+using System.Threading;
+using System.Threading.Tasks;
+using StellaOps.Notify.Queue;
+
+namespace StellaOps.Notify.Worker.Handlers;
+
+public interface INotifyEventHandler
+{
+    Task HandleAsync(NotifyQueueEventMessage message, CancellationToken cancellationToken);
+}