Deprecate the unnamespaced version and move it to includes/compat.
Bug: T147167
Depends-On: I39c805bfb98b32f32f3d0dc1eee9e823afe1c21a
Change-Id: I3780c7adf51683f3f7adb35a88f9a25a0a2e2530
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