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
Change-Id: I6763d4b6e51cf354b01ee5bfb5d37114394f3063