Move permission checks out of synchronized block

SubscriptionController#getSubscriptionInfoListFromCacheHelper is
invoked by a majority of the AIDL methods to obtain SubscriptionInfo
objects. This commit cuts down on lock contention by performing a
majority of the permission checks before the synchronized block;
with this only a single carrier privilege check may be required for
each subscription.

Fixes: 157642567
Bug: 173421434
Test: atest SubscriptionControllerTest
Test: Manually invoked test app with multiple background threads
      invoking SubscriptionManager methods to query for
      SubscriptionInfo objects; saw an average 45-50ms improvement
Change-Id: I4d738955125ea4d39252fa582c41139fc5f6f784
Merged-In: I4d738955125ea4d39252fa582c41139fc5f6f784