Organization wide setting for public/private repos upon creation

Currently there is a registry wide setting to control whether repos are public or private upon creation 

https://github.com/quay/quay/blob/0de7f6f5deb39e3b8dfec22d8ddbb709b15d5440/config.py#L791

This RFE is to add a new option in a organisation to control if repos are public or private 

Use case is mirroring OCP operators adds a lot of new repositories which are currently private. Customer wants to open these up to public whilst maintaining private repos registry wide