Before this change the WBWRenderer did not update the application model
if the information that the shell was maximized, only during dispose
this information was updated.

This lead to outdated information in the application model and forces
clients which are interested in the actual size of the Window to check
in the Shell instead in the model.

This was introduced by
https://bugs.eclipse.org/bugs/attachment.cgi?id=183776&action=diff.

The
actual logic of restoring of size is done via a tag, so putting the size
in the application should not affect the application behavior.

This also supports the scenario in which the user re-starts the
application in maximized state, as the user can still restore to the
previous state from the application model.

Fixes #3054