add a current table in CarrierIdProvider

restructure CarrierIdProvider into two tables
1. All - a private table which stores a complete mapping of all carriers
2. Current - a public table only stores the carrier identification of the
current active subs. require no permission to query.
expose the content url to public so that apps could be
notified on carrier identity change either on background or foreground.

Bug: 72571475
Test: runtest --path CarrierIdProviderTest.java
Test: Manual
Change-Id: If2a20288e63d25343f5bb582b35564d769a4e13b