Added MQTT tester, added input service

Birdmap.BLL/Helpers/IEnumerableExtensions.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Birdmap.BLL.Helpers
+{
+    public static class IEnumerableExtensions
+    {
+        public static TSource RandomElementAt<TSource>(this IEnumerable<TSource> source, Random random = null)
+        {
+            random ??= new Random();
+
+            return source.ElementAt(random.Next(source.Count()));
+        }
+    }
+}