Make configs reusable

Maybe we could integrate a ConfigMapRef similar to the secretRef to allow users to re-use configurations. This could also be overwritten by the config section. So that we would have a priority of:

- [ ] ConfigMap, decided to hold back on configmaps for now  
- [x] Secret
- [x] Resource configs spec section
- [ ] PVC annotation override, decided to hold back on additional pvc annotations for now