Add getters to NetworkStateSnapshot

Address API council feedback, add getters to NetworkStateSnapshot
instead of exposing the bare fields directly.

(cherry picked from ag/14233655)
Bug: 183972826
Test: FrameworksNetTests
Merged-In: Id1707753b42ae88d2b95e4bd00a792609434e4f5
Change-Id: Id1707753b42ae88d2b95e4bd00a792609434e4f5
7 files changed