Add a new API to get the network ID range of IPSec tunnel interface

- Add a new API to get the network ID range of IPSec tunnel
interface.
- Use the new API in IpSecServiceTest to make sure the result is
the same. Follow-up commit will change the logic in
IpSecService#reserveNetId(), the modified test can ensure the
correctness of the new change.

Bug: 172183305
Test: atest FrameworksNetTests:IpSecServiceTest
Change-Id: Ic605e48941fc9d6482cdcd01a8adcdc9b6d586a6
4 files changed
tree: a32ef15c95e68fa00659ec81aacdc79bc7dd091f
  1. core/
  2. framework/
  3. service/
  4. services/
  5. tests/
  6. OWNERS