Remove TLS support for UWP servers because Framework does not support it.

MQTTnet.Core/Server/MqttServerTlsEndpointOptions.cs

@@ -0,0 +1,11 @@
+namespace MQTTnet.Core.Server
+{
+    public sealed class MqttServerTlsEndpointOptions
+    {
+        public bool IsEnabled { get; set; }
+
+        public int? Port { get; set; }
+
+        public byte[] Certificate { get; set; }
+    }
+}