Add status to get container repository(ies) REST API response

What does this MR do and why?

The status attribute of container repositories is already included in the response of the ContainerRepositoryDetails GraphQL API, but they are not part of the equivalent REST APIs. This status attribute is currently used to determine the status of the async deletion for a given repository. The lack of this attribute in the REST API has been identified as a problem for some users in #427032 (closed).

This change adds the status field to the response for GET /registry/repositories/:id and GET /projects/:id/registry/repositories endpoints.

The status attribute is already part of the registry/repository schema (source), and this is already tested here and here.

Related to #427032 (closed).

How to set up and validate locally

1. Find or create a container repository through the Rails console:

ContainerRepository.first
  ContainerRepository Load (2.3ms)  SELECT "container_repositories".* FROM "container_repositories" ORDER BY "container_repositories"."id" ASC LIMIT 1 /*application:console,db_config_name:main,console_hostname:Joaos-MBP.lan,console_username:jpereira,line:(pry):1:in `__pry__'*/
=> #<ContainerRepository:0x000000016904d9f8
 id: 1,
 project_id: 2,
 name: "repo-b",
 created_at: Tue, 17 Oct 2023 17:07:39.490503000 UTC +00:00,
 updated_at: Wed, 29 Nov 2023 16:11:29.494802000 UTC +00:00,
 status: nil,
 # ...

1. Set its status to e.g. delete_scheduled:

ContainerRepository.first.update! status: 0

1. Grab a PAT with api or read_registry permissions and make a call against the API:

❯ http -F gdk.test:3000/api/v4/registry/repositories/1 PRIVATE-TOKEN:"glpat-foo"
{
    "cleanup_policy_started_at": null,
    "created_at": "2023-10-17T17:07:39.490Z",
    "delete_api_path": "http://gdk.test:3000/api/v4/projects/2/registry/repositories/1",
    "id": 1,
    "location": "registry.test:5000/gitlab-org/gitlab-test/repo-b",
    "name": "repo-b",
    "path": "gitlab-org/gitlab-test/repo-b",
    "project_id": 2,
    "status": "delete_scheduled"
}

❯ http -F gdk.test:3000/api/v4/projects/2/registry/repositories PRIVATE-TOKEN:"glpat-foo"
[
    {
        "cleanup_policy_started_at": null,
        "created_at": "2023-10-17T17:07:39.490Z",
        "id": 1,
        "location": "registry.test:5000/gitlab-org/gitlab-test/repo-b",
        "name": "repo-b",
        "path": "gitlab-org/gitlab-test/repo-b",
        "project_id": 2,
        "status": "delete_scheduled"
    }
]

Notice the status attribute.

MR acceptance checklist

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