Added AIDL for cell identity

Added AIDL for CellIdentityCdma, CellIdentityGsm, CellIdentityLte
and CellIdentityWcdma. This is the preliminary change for IWLAN
refactoring as network registration state will be moving into
system API.

Test: Build
bug: 64132030
Merged-In: I6763d4b6e51cf354b01ee5bfb5d37114394f3063
Change-Id: I6763d4b6e51cf354b01ee5bfb5d37114394f3063
(cherry picked from commit 31db18a4)