After #1907 is resolved, we can create a new table to define relations between user/project and container registry.

Goal

• Every users should be capable of having container registry dedicated to itself.
• Same rule applies to project, and in this case every users residing in that project can benefit from such registries.* Along with our long-term project-first architecture, let's make m2m relationship of projects and container registries.

Technical considerations

• A project can have access to multiple container registries, and a single container registry may be shared by multiple projects.
• @fregataa How could we replace the per-project accessibility (m2m relationship) with the RBAC subsystem?