Merge changes from topic "vpn_data_accounting"

* changes:
  Move BatteryStats and StatsCompanionService to use NetworkStatsService.
  NetworkStatsService: Fix getDetailedUidStats to take VPNs into account.
  Take all VPN underlying networks into account when migrating traffic for VPN uid.
tree: 193e99c1da73d267fded35046e9b212fe7b72f9d
  1. core/
  2. services/
  3. tests/