Splits into files, adds ICacheRefresherNotificationFactory, removes Init method

src/Umbraco.Core/Cache/UserCacheRefresherNotification.cs

@@ -0,0 +1,11 @@
+using Umbraco.Cms.Core.Sync;
+
+namespace Umbraco.Cms.Core.Cache
+{
+    public class UserCacheRefresherNotification : CacheRefresherNotification
+    {
+        public UserCacheRefresherNotification(object messageObject, MessageType messageType) : base(messageObject, messageType)
+        {
+        }
+    }
+}