[qtwayland] Always update window on commit
[qtwayland] Respect windowState during creation

QWaylandWindow ignored windowState set before creation, making
showMaximized, showFullScreen, (showMinimized) ineffective.

Also remove the forced visibility initialization at QWaylandSurfaceItem init.
[qtwayland] Remove unused member
[qtwayland] Check for invalid size before calling configure

If window size was not set, configure was called with size -1,-1
which was considered non-empty by QWaylandWindowConfigure.