Add request/response for voice/data Reg 1.5

-Add a request and response for the combined data and
 voice registration states from HAL 1.5.
-Add a method in CellularNetworkService to convert the
 combined data and voice reg state.

Bug: 150783910
Test: manual sanity
Merged-In: Ib9bf2fa4b7bf99896cad82ec4b6efd4952b8913d
Change-Id: Ib9bf2fa4b7bf99896cad82ec4b6efd4952b8913d
(cherry picked from commit afdc1fa5)