Add missing copyright headers to all cs files

TestAssets/TestProjects/TestAppWithEmbeddedResources/Program.cs

@@ -1,4 +1,7 @@
-using System;
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
 using System.Linq;
 using System.Reflection;
 
@@ -14,7 +17,7 @@ namespace ConsoleApplication
 
             if (resources.Count() > 1)
             {
-                throw new Exception($"{resources.Count()} found in the assembly. Was expecting only 1.");    
+                throw new Exception($"{resources.Count()} found in the assembly. Was expecting only 1.");
             }
 
             var resourceNames = string.Join(",", resources);