Allow updating IME state atomically to make it easier for platforms
where it's atomic by its nature, like Wayland. The old API is marked
as deprecated and is routed to the new atomic API.
Co-authored-by: dcz <gilapfco.dcz@porcupinefactory.org>
Generally, winit-core doesn't know about underlying platforms, though,
some general information which will true for any implementation was
left in place.
