This deprecates the Preferences class and replaces it with
a PreferencesFactory service. Basically, all code from Preferences
is moved into DefaultPreferencesFactory. All Prefereces methods
are now either shims calling DefaultPreferencesFactory or just
throw exceptions.
Bug: T178449
Change-Id: Id0b2db0c2de0890f6e1609a9a0dca207c4600f99