Clean stale entries when deleting files.

When deleting files directly from external storage devices, remove
any matching entries from MediaStore so we don't end up showing
stale entries to clients, such as MTP/PTP.

Also handles the case where an entire directory is deleted.

Bug: 24045921
Change-Id: I802470fa1aa03e0bec147ea113f1a49e26a0f3f9