More options for disconnect (#1557)

* Expose more options in disconnect options.

* Expose more options in disconnect API.

* Refactor code.

* Expose user properties in disconnected event.

* Expose more disconnect options in server.

* Fix build errors

* Add new samples.

* Fix client cleanup

* Fix merge conflicts

Source/MQTTnet.Tests/Clients/MqttClientOptionsBuilder_Tests.cs

@@ -0,0 +1,26 @@
+// 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 System.Linq;
+using System.Text;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Client;
+
+namespace MQTTnet.Tests.Clients
+{
+    [TestClass]
+    public class MqttClientOptionsBuilder_Tests
+    {
+        [TestMethod]
+        public void WithConnectionUri_Credential_Test()
+        {
+            var options = new MqttClientOptionsBuilder()
+                .WithConnectionUri("mqtt://user:password@127.0.0.1")
+                .Build();
+            
+            Assert.AreEqual("user", options.Credentials.GetUserName(null));
+            Assert.IsTrue(Encoding.UTF8.GetBytes("password").SequenceEqual(options.Credentials.GetPassword(null)));
+        }
+    }
+}