Add validations of variable byte integers (#2214)

* Add validations and add docs

* Update release notes

* Fix build

Source/MQTTnet.Tests/Exceptions/MqttProtocolViolationException_Tests.cs

@@ -0,0 +1,24 @@
+// 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 Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Exceptions;
+
+namespace MQTTnet.Tests.Exceptions;
+
+[TestClass]
+public class MqttProtocolViolationException_Tests
+{
+    [TestMethod]
+    public void No_For_Max_Large_Variable_Byte_Integer()
+    {
+        MqttProtocolViolationException.ThrowIfVariableByteIntegerExceedsLimit(MqttProtocolViolationException.VariableByteIntegerMaxValue);
+    }
+
+    [TestMethod]
+    public void Throw_Exception_For_Too_Large_Variable_Byte_Integer()
+    {
+        Assert.ThrowsExactly<MqttProtocolViolationException>(() => MqttProtocolViolationException.ThrowIfVariableByteIntegerExceedsLimit(1726790899));
+    }
+}