Migration: excluded files need to be removed (#5485)

* WIP

* Implement Remove attribute

* Enable tests

* Fix test

* Try a shorter test name

* Try more shortened test names

* Shorten some more

* Merge issues

* Try shortinging names more

* Fix test errors related to test asset renaming

TestAssets/NonRestoredTestProjects/PJDeprecatedCompileBuiltIn/project/IncludeThis.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace ConsoleApplication
+{
+    public class IncludeThis
+    {
+        public static string GetMessage()
+        {
+            return "Hello from IncludeThis class!";
+        }
+    }
+}