Deprecate scons
This is very similar to what we did for autotools when we began the process of replacing it with meson.
This series provides two different behaviors depending on platform. For Non-windows (Linux, BSD, Haiku, etc), you'll get an error unless you provide the new force_scons argument. Even with the force_scons argument you'll get a warning. For windows you'll get a warning and a request to try meson and submit feedback.