Add option to extend the osx non-native fullscreen behind the notch to the top of the screen

[wryanzimmerman]

This just adds a boolean option: macos_fullscreen_extend_behind_notch which is checked before the osx window calculates the borders to make non-native fullscreen go all the way to the top of a mac laptop with a notch, for use-cases (like mine) where that is useful.

I was also having issues with multiple monitors making the notch-avoiding window jump up and down when the active monitor changes on the release version, but I haven't been able to check if that issue still exists on main and whether or not this option fixes it. I will once I'm back with my external monitor!