Provide the full ACK on a connection failure

There are some systems that return information on a failed exception and thus the client wants access to the full set of ACK information.  Specifically the user properties.

Source/MQTTnet/Adapter/MqttConnectingFailedException.cs

@@ -5,12 +5,13 @@ namespace MQTTnet.Adapter
 {
     public class MqttConnectingFailedException : MqttCommunicationException
     {
-        public MqttConnectingFailedException(MqttClientConnectResultCode resultCode)
+        public MqttConnectingFailedException(MqttClientAuthenticateResult resultCode)
             : base($"Connecting with MQTT server failed ({resultCode.ToString()}).")
         {
-            ResultCode = resultCode;
+            Result = resultCode;
         }
 
-        public MqttClientConnectResultCode ResultCode { get; }
+        public MqttClientAuthenticateResult Result { get; }
+        public MqttClientConnectResultCode ResultCode => Result.ResultCode;
     }
 }

Source/MQTTnet/Client/MqttClient.cs

@@ -255,7 +255,7 @@ namespace MQTTnet.Client
 
             if (result.ResultCode != MqttClientConnectResultCode.Success)
             {
-                throw new MqttConnectingFailedException(result.ResultCode);
+                throw new MqttConnectingFailedException(result);
             }
 
             _logger.Verbose("Authenticated MQTT connection with server established.");