new carrier id API

1. new APIs to getCurrentCarrierId and getCurrentCarrierName
2. new broadcast intent to notify carrier id changed
3. remove unused imports

Bug: 64131637
Test: Build
Change-Id: I3f3ca2eb2c70a50386b1cc626b6b775c1449a4e3
(cherry picked from commit 43304da43ecbc1599b8f33e7fba928ca15676fa5)
Merged-in: I3f3ca2eb2c70a50386b1cc626b6b775c1449a4e3
2 files changed