desktop-shell: Branch out the set_maximed/unset_full

And move it back to its place, as we can't differentiante between two different states: coming back from unmaxized (which makes it so we send out a widthXheight size matching that of maximized whereas we should send out 0, 0) and that we're no longer fullscreen. We land basically in the same spot in both cases, and trying one issue, creates a new one.

Moving the corner case in set_fullscreen makes it so we don't reach both cases in the same time and avoid introducing other issues.

Signed-off-by: Marius Vlad marius.vlad@collabora.com