Add an API method for clearing compat overrides on release builds

This will be useful when we want to clear overrides for apps that are no longer needed regardless of the version that is installed on device, e.g., when an app is being uninstalled, when we want to rollback an override, or when we deprecate a change-id.

In addition, rename CompatChanges#setPackageOverride to
addPackageOverrides.

Bug: 183183372
Test: atest FrameworksServicesTests:CompatConfigTest
Test: atest FrameworksServicesTests:PlatformCompatTest
Change-Id: Iff416c8b4c88b5eddc9e21c73219198d23266fa1