new SystemAPI to getSimLocale

1. expose to system API
2. refactor to support passing subId instead of read from defaultSIM and
previously inserted SIM.

Bug: 122620985
Test: cts
Merged-In: I8f78ba00abf0ef74bd2b2147755596edaee156cf
Change-Id: I8f78ba00abf0ef74bd2b2147755596edaee156cf
3 files changed