Update test and samples to use modern .NET targets and dependencies.
Fix all warnings in the solution and turn on warnings as errors to avoid getting more
Fix VS test discovery by fixing the test adaptors.
Fix an issue with the ILogger adaptor referencing an "internal" type that is not longer in newer versions of .NET. This is the one functional change in the released packages.
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Description of changes: Clean up some bit rot
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.