Add PJ support to TestAssets (#5109)

* Add PJ support to TestAssets

* Cleaning the test assets is hard, so throwing instead

* better assets filter

* PR feedback

* PR Feedback

* Fix NullRef

* Move lock to surround action + file read/write

test/Microsoft.DotNet.Tools.Tests.Utilities/TestBase.cs

@@ -53,7 +53,10 @@ namespace Microsoft.DotNet.Tools.Test.Utilities
                 {
                     var assetsRoot = Path.Combine(RepoRoot, "TestAssets");
 
-                    s_testAssets = new TestAssets(new DirectoryInfo(assetsRoot)); 
+                    s_testAssets = new TestAssets(
+                        new DirectoryInfo(assetsRoot),
+                        new FileInfo(new EnvironmentProvider().GetCommandPath("dotnet")),
+                        new FileInfo(new RepoDirectoriesProvider().PjDotnet)); 
                 }
 
                 return s_testAssets;