DesktopAura: Remove the usage of OzoneDisplay in DRWH.

We use OzoneDisplay in DRWH to query for PrimaryScreen and get it's
geometry. In Aura, we just have one Screen which can be associated to one or
more display. Now, we query PrimaryDisplay from Screen and get it's geometry.
OzoneDisplay: Remove logic in DefaultDisplaySpec

This CL removes logic related to updating spec_ in OzoneDisplay as
we don't use it and upstream has completely removed it's usage. We need to
update our revision before removing DefaultDisplaySpec. This is part of an
effort to remove all DesktopScreen usage in OzoneDisplay
DesktopAura: Make Screen implement OutputChangeObserver interface.

Currently, OzoneDisplay implements OutputChangeObserver and informs Screen
of any output changes. Eventually, goal is that OzoneDisplay will have no
information about DesktopAura, this CL makes Screen implement
OutputChangeObserver interface. Now, the only reference to DesktopScreen
in OzoneDisplay is it's creation.
Cleanup: Remove unnecessary display include in EGLWindow.
WaylandDisplay: Make Destroy and Create functions private.

Any Widget state change needs to be handled via WindowStateChangeHandler
interface. We have CreateAcceleratedSurface and DestroyWindow which shouldn't
be used outside WaylandDisplay now. This CL makes these functions private.
Most of the changes are related to rearranging code in order to ensure the
order of declaration and implementation are same.
OzoneDisplay: Move RealizeAcceleratedWidget logic to WaylandDisplay.

We moved all Windowstate change handling to WaylandDisplay. For
completeness, this patch moves RealizeAcceleratedWidget to WaylandDisplay
too.