layout: Send dimensions when setting up property as fullscreen

layout: Send dimensions when setting up property as fullscreen

Instead of doing it at commit time, do it right after getting the xdg
toplevel surface such that clients can use it from the beginning.

This now includes fullscreen, besides regular desktop roles, and it
avoid mapping the fullscreen upon commit if the dimensions do not really
match up.

Bug-AGL: SPEC-4339
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Change-Id: I7185b10770c69d1d6572b0bc025c4a58fe431c67
(cherry picked from commit 13ac8bab43fffd002196d3a6760eefaa8944def2)