Add events aggregator

Hcs.WebApp/BackgroundServices/ResultGetState.cs

@@ -5,8 +5,6 @@ namespace Hcs.WebApp.BackgroundServices
 {
     public class ResultGetState
     {
-        public delegate void OperationEnded(int operationId, int campaignId, DateTime endedAt, string failureReason);
-
         private readonly ConcurrentQueue<Operation> operationsInQueue = new();
         private readonly HashSet<Operation> operationsInProcess = [];