Add support for loading a static overrides file located in /product.

Note that the dynamic overrides file in the /data/misc/appcompat will be
loaded after the static file is loaded and take precedence over it
(overrides in the dynamic file will override corresponding ones in the
static file).

This static file will be used to inject hard coded per app configuration.

Bug: 180396167
Test: atest FrameworksServicesTests:CompatConfigTest
Change-Id: I73569744e718274255885d270ab8285956647f4c