Add operation executor

Hcs.Broker.Mock/Api/MockNsiCommonApi.cs

@@ -21,5 +21,12 @@ namespace Hcs.Broker.Mock.Api
 
             return null;
         }
+
+        public async Task<string> RequestExportNsiItemAsync(int registryNumber, ListGroup listGroup, CancellationToken token = default)
+        {
+            await Task.Delay(3000, token);
+
+            return Guid.NewGuid().ToString();
+        }
     }
 }