Currently, unprivileged apps can call getAllNetworks() to see
all networks on the system, even networks that do not apply to
them. Allow them to do this via NetworkCallbacks as well.
This is the last piece of information that was only available
through getAllNetworks, so this CL deprecates that API.
Bug: 187921303
Test: new unit tests
Test: CTS test in other CL in topic
Change-Id: I30f1021927d3c8eae6525116c61ff4a4acecff6d
d82c1ec110