Refactor benchmarks (#1601)

Source/MQTTnet.Benchmarks/MessageDeliveryBenchmark.cs

@@ -1,5 +1,8 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
 using BenchmarkDotNet.Attributes;
-using BenchmarkDotNet.Jobs;
 using MQTTnet.Client;
 using MQTTnet.Server;
 using System;
@@ -8,14 +11,10 @@ using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 
-
 namespace MQTTnet.Benchmarks
 {
-    /// <summary>
-    /// Create a number of topics, publish, subscribe, and wait for response
-    /// </summary>
     [MemoryDiagnoser]
-    public class MessageDeliveryBenchmark
+    public class MessageDeliveryBenchmark : BaseBenchmark
     {
         List<MqttApplicationMessage> _topicPublishMessages;