Add more bindings to sys/windows

[Lperlind]

More bindings to kernel32 and user32.

[Lperlind]

Looks like it conflicts with raylib :/

[Hyrtwol]

fyi had the same issue the work a-round was

when !intrinsics.is_package_imported("raylib") {
    ShowCursor :: proc(bShow: BOOL) -> INT ---
}

not ideal but usually you don't use raylib and win32 at the same time :p I think if you rebase up this pr should work.