WindowManager: Set 'inert' as well as 'aria-hidden' when opening modals
WindowManager: Set 'inert' as well as 'aria-hidden' when opening modals

This feature is coming soon to most major browsers, so we can
set the attribute in anticipation of this.

Bug: T307995
Change-Id: Ie402f807fdc070b25b3223489896b724f4e29b5d

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui