Exposing NetworkRegistrationInfo for PS service

This patch exposes WWAN and WLAN registration status
information so that callers can understand:
-Roaming status
-Searching status
-Available services, such as emergency and voice calling

Bug: 123099466
Fixes: 21208250
Test: make && make offline-sdk-docs
Change-Id: I1421b638f1835962de8e4ba18bdf75615d37ebe5