Route whether or not a window is fullscreen down into GPUI

This still needs to be able to invalidate things to be useful
but it's a good first cut at just making the information available
to platform-agnostic code

Co-authored-by: Mikayla <mikayla@zed.dev>
ab760493cfForLoveOfCats committed on 8/9/2022, 11:03:12 PMparentae8dd1e
4 files changedLine totals unavailable