Add CMake version of building a ntcore desktop app

The current example is Gradle-based, which can make it hard to integrate other libraries.

cmake version is here: https://www.chiefdelphi.com/t/unable-to-use-windows-libraries-with-wpilib-and-vs-code/440595/2

Needs to use `set (WITH_CSCORE OFF CACHE INTERNAL "")` etc instead of plain set().