Add BroadcastTime tied with system UTC time

:Release Notes:
Added additional bit of information to keep broadcast time.

:Detailed Notes:
- class to store/retrieve broadcast time aligned to system time.
- hook on system time change to adjust offsets for broadcast time and
  keep them the same after time jump effect.

:Testing Performed:
Desktop build with https://g2g.palm.com/3596

:QA Notes:

:Issues Addressed:
[GF-40247] Support API to send XDS time to luna-sysservice
[GF-40249] Provide API to obtain EBT from luna-sysservice

Open-webOS-DCO-1.0-Signed-off-by: Nikolay Orliuk <nikolay.orliuk@lge.com>
Change-Id: I84b443d2615aa781eaf7445d161c05494860ce28
Reviewed-on: https://g2g.palm.com/3595
Reviewed-by: Keith Derrick <keith.derrick@lge.com>
Tested-by: Keith Derrick <keith.derrick@lge.com>