xwayland: update stacking order in move_to_front/back()

xwayland: update stacking order in move_to_front/back()

Currently xwayland views are restacked on top of the XWayland server
stacking order when activated (i.e. focused). This is wrong because
focus/raise are independent concepts (though often occurring together).
The stacking order should be updated when the view is raised/lowered,
not when the view is focused.

Work is in progress elsewhere (draft PR) that will result in views more
often being raised without being focused. Without this fix, those views
don't get restacked properly, resulting in clicks "passing through" to
views underneath.