Add debug notifications

This adds a test notif only available in debug mode + endpoint `/Notifications/GenerateJunk` that generates x amount of notifications.

BTCPayServer/Controllers/NotificationsController.cs

@@ -87,7 +87,18 @@ namespace BTCPayServer.Controllers
 
             return new EmptyResult();
         }
+#if DEBUG
+        [HttpGet]
+        public async Task<IActionResult> GenerateJunk(int x = 100)
+        {
+            for (int i = 0; i < x; i++)
+            {
+                await _notificationSender.SendNotification(new AdminScope(), new JunkNotification());
+            }
 
+            return RedirectToAction("Index");
+        }
+#endif
         [HttpGet]
         public IActionResult Index(int skip = 0, int count = 50, int timezoneOffset = 0)
         {

BTCPayServer/Hosting/BTCPayServerServices.cs

@@ -246,7 +246,10 @@ namespace BTCPayServer.Hosting
 
             services.AddSingleton<INotificationHandler, InvoiceEventNotification.Handler>();
             services.AddSingleton<INotificationHandler, PayoutNotification.Handler>();
-
+            
+#if DEBUG
+            services.AddSingleton<INotificationHandler, JunkNotification.Handler>();
+#endif    
             services.TryAddSingleton<ExplorerClientProvider>();
             services.TryAddSingleton<Bitpay>(o =>
             {

BTCPayServer/Services/Notifications/Blobs/JunkNotification.cs

@@ -0,0 +1,19 @@
+#if DEBUG
+using BTCPayServer.Models.NotificationViewModels;
+
+namespace BTCPayServer.Services.Notifications.Blobs
+{
+    internal class JunkNotification
+    {
+        internal class Handler : NotificationHandler<JunkNotification>
+        {
+            public override string NotificationType => "junk";
+
+            protected override void FillViewModel(JunkNotification notification, NotificationViewModel vm)
+            {
+                vm.Body = $"All your junk r belong to us!";
+            }
+        }
+    }
+}
+#endif