Address comments on NetworkStack AIDL v6

Address issues found during AIDL review:
 - Rename clientAddr to singleClientAddr
 - Do not use a ParcelableBundle for notifyNetworkTested or
   notifyDataStallSuspected; instead use AIDL parcelables for stronger
   backwards compatibility guarantees.

Test: atest NetworkMonitorTest ConnectivityServiceTest
      ConnectivityServiceIntegrationTest, manual
Bug: 153500847
Change-Id: Id9b71784e5f6294d203230e57737979e063ff0f8