build(deps): Replace winapi by windows-sys

[caspermeijn]

winapi has not been updated for four years. windows-sys seems to have a good maintainer. winit also uses windows-sys.

The Windows API calls are not changed. It just uses a different bindings library.

• I have followed the instructions in the PR template

Alternative

I tried to remove the Windows API calls from this crate. As stated in a comment, winit can do some of the work, but I was unable to fix winit enough to use that. My poor knowledge of Windows API doesn't help with that.

// We would get fairly far already with winit's `set_window_icon` (which is exposed to eframe) actually!
// However, it only sets ICON_SMALL, i.e. doesn't allow us to set a higher resolution icon for the task bar.
// Also, there is scaling issues, detailed below.