Add a new API in BatteryStatsManager for connectivity service

Connectivity service(CS) is going to be a mainline module and
currently it uses IBatteryStats to communicate with battery
stats service directly. CS cannot use this way after becomes
a mainline module so add new system APIs to communicate with
battery stats service through BatteryStatsManger.

The new API reportNetworkInterfaceForTransports requires
system-only permission NETWORK_STACK or MAINLINE_NETWORK_STACK
so that given the only caller was in ConnectivityService.

This change only add new surface, the usage in CS will be
updated in follow-up CL.

Bug: 171686421
Test: builds, boot, mobile and wifi work.
Change-Id: Ifbd4a9784ed7664751e69d530f8204e292fa6b39