MediaStore API and docs polishing.

Initial efforts at cleaning up MediaStore docs, including deprecation
of crufty methods, and annotations to communicate stored units.

Bug: 120429729, 124013019
Test: atest cts/tests/tests/provider/src/android/provider/cts/MediaStore*
Change-Id: I87828f19030b6b354472c1b3ce767de166f86134
5 files changed