Add mutation to update container virtual registry

Create a GraphQL mutation to update a container virtual registry.

Mutation name: containerVirtualRegistryUpdate

REST API reference: https://docs.gitlab.com/api/container_virtual_registries/#update-a-virtual-registry

GraphQL reference for upstream create: https://docs.gitlab.com/api/graphql/reference/#mutationcontainerupstreamcreate

Reference issue for the create container virtual registry: #582485 (closed)