Get ANR delay from the MediaProvider

StorageManagerService registers an AnrController with the
ActivityManager so that when an app is about to ANR, it receives a
callback to get an ANR delay. This request is forwarded to the
MediaProvider that checks if the uid is blocked on a transcoding job
and if so returns an appropriate delay

Bug: 170486601
Test: Manual
CTS-Coverage-Bug: 179658703
Change-Id: I9787d8127ed9757a23be7337bd4454a488d44141