Use consistent StyleCop configuration across .NET samples

[stevengum]

Are this. part of the samples' StyleCop configuration?

Originally posted by @stevengum in https://github.com/microsoft/BotBuilder-Samples/pull/2674

I started with the existing adaptive samples. I'm open to changing/ updating to be consistent but we need to do it across the board. Let's file a ticket to track any code style related fixes required to this + adaptive samples?

Originally posted by @vishwacsena in https://github.com/microsoft/BotBuilder-Samples/pull/2674