Implement Special app access in permissionController

Test: Navigate to the Files and Media permission Screen. Ensure that
pre-P apps have "all files access", that all P and Q apps have access
media only, unless they have the legacy storage app op, and that all R
apps have a tri-state permission if they request the special app access.
Bug: 147585980

Change-Id: Ib9909f4f8ca2832e1303371bd6261013ab62be73