New: Add more information to Webhook payload

Fixes #5104

Co-Authored-By: Mark McDowall <markus101@users.noreply.github.com>

src/NzbDrone.Core/Notifications/Webhook/WebhookImportPayload.cs

@@ -1,3 +1,5 @@
+using System.Collections.Generic;
+
 namespace NzbDrone.Core.Notifications.Webhook
 {
     public class WebhookImportPayload : WebhookPayload
@@ -7,5 +9,6 @@ namespace NzbDrone.Core.Notifications.Webhook
         public bool IsUpgrade { get; set; }
         public string DownloadClient { get; set; }
         public string DownloadId { get; set; }
+        public List<WebhookMovieFile> DeletedFiles { get; set; }
     }
 }