Adds EventState to the event args instead of trying to change the AdditionalData which is a breaking change. Updates FileService and ContentService to use one event arg insteance for both before/after events so that the EventState flows and so we are allocating less objects.

src/Umbraco.Web/Routing/RedirectTrackingEventHandler.cs

@@ -271,6 +271,7 @@ namespace Umbraco.Web.Routing
 
         private static void ContentService_Moving(IContentService sender, MoveEventArgs<IContent> e)
         {
+            //TODO: Use the new e.EventState to track state between Moving/Moved events!
             Moving = true;
         }