Add NUnit test chassis and Powershelll test generator scripts

Il2CppTests/TestSources/Methods.cs

@@ -0,0 +1,22 @@
+/*
+    Copyright 2017-2019 Katy Coe - http://www.hearthcode.org - http://www.djkaty.com
+
+    All rights reserved.
+*/
+
+using System.Text;
+
+namespace Il2CppTests.TestSources
+{
+    internal class Test
+    {
+        // A parameter-less method
+        public void ParameterlessMethod() { }
+
+        // Method with value type return type
+        public int ValueTypeReturnMethod() => 0;
+
+        // Method with reference type return type
+        public StringBuilder ReferenceTypeReturnMethod() => new StringBuilder();
+    }
+}