Expose netId by adding getter API

Bug: 151156820
Test: m
      atest TetetheringTests

Clean CP from ag/10747732

Change-Id: Ieb1483c146aa2f7d8f251157e6e81d71c44ae899
Merged-In: Ieb1483c146aa2f7d8f251157e6e81d71c44ae899
4 files changed