Extend onDnsEvent callback to report more fields.

When native layer reports onDnsEvent, netId, eventType and
returnCode are available only in NetdEventListenerService, but
not for the clients who register event on it.

Thus, extend the callback to give clients more detail on the
network the look up was performed on and the result of the
lookup.

Bug: 113916551
Test: 1. runtest frameworks-net
      2. runtest frameworks-services -c com.android.server. \
         net.watchlist.NetworkWatchlistServiceTests
Change-Id: If7beecea50e1baf18cb5c6775ad3ecb1a60b312a