Fix MSTest Packages for test utilities

[pauld-msft]

Dotnet pack is failing, since testhost.dll is mistakenly in the TestUtilities Nuget package.

The assembly 'content\testhost.dll' is not inside the 'lib' folder and hence it won't be added as a reference when the package is installed into a project. Move it into the 'lib' folder if it needs to be referenced.

https://learn.microsoft.com/en-us/dotnet/core/testing/unit-testing-mstest-getting-started mentions

If you are creating a test infrastructure project that is intended to be used as a helper by multiple test projects, you should install the MSTest.TestFramework and MSTest.Analyzers packages directly into that project.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 88.9%. Comparing base (9297f05) to head (a838468).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1234 +/- ## ===================================== Coverage 88.9% 88.9% ===================================== Files 359 359 Lines 27668 27668 Branches 1784 1784 ===================================== Hits 24610 24610 Misses 2674 2674 Partials 384 384 ```

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[github-actions[bot]]

👋 Hi! It looks like you modified some files in the Detectors folder. You may need to bump the detector versions if any of the following scenarios apply:

• The detector detects more or fewer components than before
• The detector generates different parent/child graph relationships than before
• The detector generates different devDependencies values than before

If none of the above scenarios apply, feel free to ignore this comment 🙂