post migration cleanup (#4449)

* Create tests

* Basic scenario working & tested

* Feature Complete

* prevent build of intentionally broken test asset

* Update migrate command backup

* PR Feedback

* Move negative test to negative test directory

* Fix tests

* make test output directories unique

* Merge Conflict

* make backup the default behavior

* Pass2Fail

* Remove tests' PJ dependency

test/Microsoft.DotNet.Tools.Tests.Utilities/Commands/MigrateCommand.cs

@@ -0,0 +1,29 @@
+// 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 Microsoft.DotNet.Cli.Utils;
+
+namespace Microsoft.DotNet.Tools.Test.Utilities
+{
+    public sealed class MigrateCommand : TestCommand
+    {
+        public MigrateCommand()
+            : base("dotnet")
+        {
+
+        }
+
+        public override CommandResult Execute(string args="")
+        {
+            args = $"migrate {args}";
+
+            return base.Execute(args);
+        }
+
+        public override CommandResult ExecuteWithCapturedOutput(string args = "")
+        {
+            args = $"migrate {args}";
+            return base.ExecuteWithCapturedOutput(args);
+        }
+    }
+}