ecore_wl2: Synchronize state with surface commits

ecore_wl2: Synchronize state with surface commits

This is really several inseparable commits mashed together, as doing this
a piece at a time would introduce broken intermediate revisions.

Double buffer incoming "configure" state from the compositor so it's held
back during asynchronous render and processed at frame completion.

Hold off on certain requests if their API has been invoked during async
render.

This should fix a lot of races, cosmetic issues, issues where weston can
kill our clients for acking configure (or not) at bad times, etc.