Support to query TYPE_WIFI usage with subscriberId

Previous the API ignores subscriberId when network type is WIFI.
Allow caller to call querySummaryXXXX with TYPE: WIFI
+ subscriberId: IMSI to get carrier merged wifi usage which matches the wifi
network with the given IMSI.

Bug: 176396812
Test: atest -c NetworkStatsServiceTest
Change-Id: Ia033521a24e2bb56182d74a41bb2b39710571782

core/java/android/app/usage/NetworkStatsManager.java

@@ -644,7 +644,10 @@ public class NetworkStatsManager {
                         : NetworkTemplate.buildTemplateMobileAll(subscriberId);
                 break;
             case ConnectivityManager.TYPE_WIFI:
-                template = NetworkTemplate.buildTemplateWifiWildcard();
+                template = subscriberId == null
+                        ? NetworkTemplate.buildTemplateWifiWildcard()
+                        : NetworkTemplate.buildTemplateWifi(NetworkTemplate.WIFI_NETWORKID_ALL,
+                                subscriberId);
                 break;
             default:
                 throw new IllegalArgumentException("Cannot create template for network type "