t Convert Test Assets to Microsoft.NETCore.App

fix dotnet-compile-fsc failures

fix test failures

test/dotnet-test.UnitTests/GivenATestCommand.cs

@@ -16,6 +16,7 @@ namespace Microsoft.Dotnet.Tools.Test.Tests
         private static readonly string ProjectJsonPath = Path.Combine(
                 AppContext.BaseDirectory,
                 "TestAssets",
+                "TestProjects",
                 "ProjectWithTests",
                 "project.json");