Register for and handle screen events delivered through BPS

Register for and handle screen events delivered through BPS

Delegates actual event inspection and reaction to the screen event
handler class already used by the PPS screen event handler

Change-Id: Ic07efa1de3f6b452f3091e901bd8a577175e3cf0
Reviewed-by: Rafael Roquetto <rafael.roquetto@kdab.com>
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>