cellbroadcast provider refactor

1. expose proper APIs to query framework cellbroadcast provider
2. export framework cellbroadcast provider
3. new URI with proper permission check

Bug: 135956699
Test: Build & Manual
Change-Id: I2cf0d0314e5f0283e6bde71407a1d43d7373a2e7
(cherry picked from commit fc0a165b8efc360c17fe22e94211038590a3f30c)
Merged-in: I2cf0d0314e5f0283e6bde71407a1d43d7373a2e7
3 files changed