Add the upstream URL to the remote repository header

What does this MR do and why?

This MR adds the upstream URL to the header of a remote repository, under the name and beside the format logo, with a button to copy it. Hosted repositories look exactly as before.

Three things worth knowing about how it behaves:

• The URL is text, not a link. It is an outbound address an operator configured. Making it clickable would invite people to follow it.
• Long URLs shorten from the middle, so you keep the host and the end of the path, which is what tells two upstreams apart. Hovering shows the whole thing, and the copy button always copies the full URL.
• If a remote repository has no settings, the line is hidden rather than showing a placeholder.

References

Work item: gitlab-org#22453

Screenshots or screen recordings

Before	After
Remote repository edit page

How to set up and validate locally

1. Enable the feature flag in the rails console:

   Feature.enable(:artifact_registry_ui)

2. Visit an organization's Artifact Registry and open a remote repository's detail page.

3. The upstream URL renders beneath the repository name, as text, with a copy button beside it.

4. Narrow the window: the URL shortens from the middle rather than wrapping or widening the header.

5. Open a hosted repository and confirm no URL line renders.

MR acceptance checklist

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Behind the artifact_registry_ui feature flag, which is disabled, so there is no changelog entry.

Related to gitlab-org#22453