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
2 files changed
tree: 964a97ab76f9d53044a39e9ccae86dfb58868928
  1. framework/
  2. service/
  3. OWNERS