[Feature] Add support for unit testing

[shweaver-MSFT]

Describe the problem this feature would solve

The project could use some unit tests! I specifically want to add tests for our providers and helpers (e.g. WindowsProvider, RoamingSettingsHelper).

Describe the solution

Check out the UnitTest setup in WCT and do something similar here.

Describe alternatives you've considered

Additional context & Screenshots