Migrate to `windows`/`-sys` crate

[ok-nick]

winapi is a community-maintained crate for windows bindings that has received only a single update in the last year. Microsoft has officially released their own set of bindings providing both a raw low-level crate, windows-sys, and a higherish-level crate (with some helper traits and etc), windows. As the general Rust ecosystem is migrating to the new windows crates, ctrlc should follow. It would be preferable to use the windows-sys crate over the windows crate as it should cut down on any extra compilation times. Additionally, since the scale of this project is relatively small, I don't think it would benefit from any abstractions made by the windows crate.

[Detegr]

Thanks for the info. I agree this would be a good thing to do.

[Detegr]

Migration done in #92