Get details of a container virtual registry

Proposal

We add a query to get the details of a container virtual registry given a registry ID.

query {
  virtualRegistryContainerRegistry(id: "gid://gitlab/VirtualRegistries::Container::Registry/5"){
    id
    description
    name
    registryUpstreams {
      id
      position
      upstream {
        id
        username
        url
        name
      }
    }
  }
}

Maven reference: #557592 (closed)