[FEATURE]:Include additional columns from junction tables in many-to-many relations

### Feature hasn't been suggested before.

- [x] I have verified this feature I'm about to request hasn't been suggested before.

### Describe the enhancement you want to request

I love the new way to define relations, however I'd like to see the way to include additional columns from junction tables in case of `many-to-many` relations. According to the docs we need to use `through` to simply bypass the junction table, but it would be great to have an option to include additional columns from the junction table. Thank you for doing an amazing job.