Fixes and improvements for MSVC, add Windows builds to CI

[chausner]

This fixes a couple of issues that prevented the code from compiling with Visual Studio:

• DUPLO_VERSION is not defined in the vcxproj which makes the code not compile. I chose to make the define optional.
• Release builds with MSVC fail due to a compiler warning (treated as error).
• Updated the platform toolset version for Visual Studio 2022
• Some source and header files were missing in Duplo.vcxproj which I added.

I also took the chance of adding some tweaks and improvements to CMakeLists.txt so that it works with MSVC, as well.

Finally, I added Windows builds to CI.

[dlidstrom]

@chausner Thanks a TON!!! This was on my bad conscience for years. I'll happily merge this 💪🏻