Migrate common test code to separate NuGet package

[cbcrouse]

Issue #8 calls out adding code coverage to at least 80% but several common test classes are used across several repositories and the test coverage already exists in other repositories.

• [ ] Extract the common testing files into their own repository/solution
• [ ] Setup the pipelines to produce a NuGet package
• [ ] Consume the NuGet package in other repositories and remove the local references