Carrier merged wifi network is a specific cerrier wifi network
which provides the same user experience as mobile.
To support data usage accounting for carrier merged wifi,
the change provide several APIs in NetworkTemplate:
1. extend buildTemplateWifi so it could be used for matching
wifi networks with subscriber Id (IMSI).
2. add buildTemplateCarrier to let
NetworkPolicyManagerService creates a single policy for
a given carrier regardless of network type.
Bug: 176396812
Test: atest -c NetworkTemplateTest
Test: atest -c NetworkStatsServiceTest
Test: Manual Test with test code on mobile and wifi network.
1. buildTemplateCarrier includes the carrier wifi and
mobile usage
2. buildTemplateWifi can get carrier wifi usage and support the
filter via subscriberId
Change-Id: I667b4adf3eec0bdd3a7385109dd8c1fae8e7be32
f5beb8fcb0