QLowEnergyController: Introduce AuthorizationError

intended to distinguish an arbitrary disconnection
from disconnection due to insufficient authorization/encryption

Change-Id: Ifcf73d0444fe6fd3a8d5d90155f3db572d6e23d1
Reviewed-by: Evgeniy Gagarin <eeiaao@gmail.com>
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>