This adds some plumbing to get the "default" paint flags for regular
stage painting, where one either wants to paint the overlay, or not.
If inhibited, the 'no-cursors' paint flag is used, otherwise the 'none'
flag. This will be used to allow having a per stage view hw cursor
state.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2777>