Added EndPoint RemoteEndPoint {get;} property to channel (#2111)

* Added EndPoint RemoteEndPoint{get;} property

* Reformat code

* Reformat code

---------

Co-authored-by: christian <6939810+chkr1011@users.noreply.github.com>

Source/MQTTnet.Tests/Mockups/MemoryMqttChannel.cs

@@ -2,10 +2,12 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using Microsoft.AspNetCore.Http;
 using MQTTnet.Channel;
 using MQTTnet.Internal;
 using System.Buffers;
 using System.IO;
+using System.Net;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
@@ -26,7 +28,7 @@ namespace MQTTnet.Tests.Mockups
             _stream = new MemoryStream(buffer);
         }
 
-        public string Endpoint { get; } = "<Test channel>";
+        public EndPoint RemoteEndPoint { get; set; }
 
         public bool IsSecureConnection { get; } = false;