Return copies for get methods

NetworkRegistrationInfo and ServiceState are not
immutable class. Their get methods should return a new
copy of object so the caller won't modify its state.

Bug: 130538118
Test: Unit tests + manual

Merged-In: I51662a92b0b6189a8c8aa017085affedac417190
Change-Id: I51662a92b0b6189a8c8aa017085affedac417190
(cherry picked from commit 37538594)