Include settings app compat config in the build.

This ensures that any compact changes defined in settings work correctly
at runtime.

Include the config in the system_ext partition rather than system to
avoid breaking rules about where we're allowed to put things.

Test: m
Test: Check compat changes appear in dev settings UI.
Change-Id: I4a6dc6bfcc5de1f68e97faf905ee94b35bde5d11