ConnectivityManager#registerNetworkAgent gains an argument

This is to support local network agents. See aosp/2752269 for
the original implementation (reverted for the lack of this
patch) and aosp/2792436 for the reapply.

Test: Patch in the connectivity changes and run
      all FrameworksTelephonyTests. It doesn't pass without this
      patch and it passes with it.
Change-Id: I96c0f6d81a4f826425d098e28171f65a5d722f15