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.

As part of moving notifyNetworkTested to using a parcelable the test
result int is split into two: the actual evaluation result, and the
probesSucceeded int. It used to contain both as a bit mask, which does
not make sense if probesAttempted is in a separate int itself.

Test: atest NetworkMonitorTest ConnectivityServiceTest
ConnectivityServiceIntegrationTest, manual
Bug: 153500847

Change-Id: I4aac6ff7432472f8a9345fb5785c6314ec8946e4