Provide a hybrid ServiceState consisting of base phone object and IMS SS.

Original code used either base phone SS or IMS phone SS (if base phone
was not in service). Now merge the two to provide the baseline SS information
from the base phone and only the voice SS information from the IMS phone
(and only if the base phone is not in service).

Bug: 17627405
Change-Id: I3ace832f9be700282105a52088715b8039e56666