Push firewall rules up to ConnectivityService.

getActiveNetworkInfo() and friends already know how to augment their
results to help apps detect when network access is blocked.  This
change wires up the new app-idle and device-idle firewall rules to
be reported through these APIs.

This also causes other platform tools like DownloadManager and
SyncManager to respect these new policies.

Bug: 24050462
Change-Id: Id9517b0b70be7e3ca2ab27bed8049db916e4d829