Iteration on contributed media APIs.

Offer an explicit DELETE_CONTRIBUTED_MEDIA flag that can be used when
uninstalling an app to indicate that any contributed media should be
deleted.

Adjust APIs to accept a specific UserHandle so we can pre-flight
check for valid UserManager state.

Bug: 116344240
Test: atest android.provider.cts.MediaStoreTest
Change-Id: Ief0ba27c913791d60f86a5d7252525c9c4539fc6