Allow DS core fields to have alterable settings, include them in field_info_instance_settings()

I'm using the Field Formatter Class module and it would be nice to have the core DS fields (the ones that show up when you select a layout) to allow other modules to alter the "field's" settings. Maybe just adding them somehow to the list when field_info_instance_settings() is called might be appropriate?

I'll also mention that we're seeing some some weird warnings if using DS core fields: 🐛 Compatibility with Display Suite Closed: outdated

The only other issue I could find that might somewhat resemble this issue: #1867828: Conditions on Display Suite fields are not behaving nicely + obsolete saving of field settings →