Improve MediaStore CloudMediaProvider (CMP) APIs

Previously, we had the following poorly named APIs on MediaStore:
1. getCloudProvider: Leaked the CMP authority to apps
2. notifyCloudEvent: Too broad

Now:

- Renamed 1) to isCurrentCloudMediaProvider and added
isSupportedCloudMediaProvider
- Renamed notifyCloudEvent to notifyCloudMediaChangedEvent

Test: atest CloudPhotoPickerTest
Bug: 214029148
Change-Id: Ia5534162b0fb38e18fc05dd4df6f98ab7ec8e4f0
5 files changed