Restrictions saved as key/value pairs, mostly booleans right now
but might be expanded to other types later.
Save and restore restrictions in the user manager service.
Enforce some of the restrictions at the framework level. Some
are enforced (also) at the app level, such as in Settings.
Change-Id: Id11ffe129cb6a177e094edf79635727388c26f40
This helps reduce the pressure on framework.jar, and makes it clear
that it should only be used by the system_server.
Bug: 7333397
Change-Id: I0858904239535380fbf30562b793e277d8c3f054