Ported some of the python fuzz tests to C#

* Refactored the test runner to use attribute based test discovery
* Ported value and vtable/object fuzzing tests from python to C#

tests/FlatBuffers.Test/Lcg.cs

@@ -0,0 +1,26 @@
+namespace FlatBuffers.Test
+{
+    /// <summary>
+    /// Lcg Pseudo RNG
+    /// </summary>
+    internal sealed class Lcg
+    {
+        private const uint InitialValue = 10000;
+        private uint _state;
+
+        public Lcg()
+        {
+            _state = InitialValue;
+        }
+
+        public uint Next()
+        {
+            return (_state = 69069 * _state + 362437);
+        }
+
+        public void Reset()
+        {
+            _state = InitialValue;
+        }
+    }
+}