Add mutation to update container virtual registry

What does this MR do and why?

This adds a new GraphQL mutation containerVirtualRegistryUpdate to update a container virtual registry.

References

• Add mutation to update container virtual registry (#582486)

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Create a new container virtual registry, using API or in the Rails console:

   VirtualRegistries::Container::Registry.create(group: group, name: 'foo', description: 'bar')

2. Run the mutation in GraphQL explorer:

   mutation {
     containerVirtualRegistryUpdate(input:{id: <REGISTRY_ID>, name:"New registry name", description:"New registry description"}) {
       errors
       registry {
         id
         name
         description
       }
     }
   }

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