Add ConnectivityManager.reportNetworkConnectivity() API

This new API allows reporting networks that are perceived to provide Internet
connectivity and networks that are not.  This allows the framework to avoid
needlessly reevaluating networks where the apps perception matches the
framework's perception.  This was not possible with the prior API,
reportBadNetwork.

Bug: 16214361
Change-Id: Id4409bd7538854bd837231fb50e693c10a62b4f2