Add Testing

[tonyb983]

Small request, would it be possible for you add, or demonstrate how one would add, a barebones testing setup to this template? I think it's always good to encourage / "remind" people that testing is important and should be in the forefront of your mind when writing code. I think having an already existing test folder and test target(s) for CMake would be a great thing to have within this project.

Also, perhaps having a few examples of adding and using dependencies (either through a package manager like vcpkg or bazel, or through a CMake fetch-like functionality) might be helpful for any others looking to have as many training wheels as possible.

That being said, I would like to thank you for this repo / template. I am also a person who has always loved C++ but felt a bit "left out" so to speak when it comes to actually using or experimenting with it because I am a) on Windows and b) unable to install the full Visual Studio IDE. VSCode has been my goto when it comes to lightweight IDE-like experience, but it has always been a big pain point getting it working with C++ and CMake. Being able to use this repo and immediately having everything work perfectly has been a refreshing experience.