Add NDK API for getprocnetwork

The API is the getter couterpart for setprocnetwork.
Use it in NetworkUtils so that the NDK API can be the source of truth
for the process network.

Original change (project moved):
Ie8f68cf1fa57deddb63324c1abf3d6fd5b0ef500

Bug: 171540887
Test: atest CtsNetTestCases
      Tests in change I311b58585033c2ca50ce5477ea9cd94b6f127507
Merged-In: I3c2563d4ae4e3715d0c6270344ba8f7ef067872f
Change-Id: Iaf255f4aa29fd2ae02770baea5548ee8d5d407f2
3 files changed