Adds menu entry for Google Artifact registry

What does this MR do and why?

• Adds feature flag gcp_artifact_registry
• Adds Saas feature google_artifact_registry
• when the above is true & container registry is enabled, it adds a new menu item to the project sidebar, allowing users to access and manage their Google Artifact Registry images.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Enable container registry in the gdk https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/main/doc/howto/registry.md#set-up-container-registry-to-display-in-ui-only
2. Simulate a SAAS instance in local GDK
3. In rails console enable the experiment

   Feature.enable(:gcp_artifact_registry)

4. Visit Project > Deploy > Google Artifact registry

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #425154 (closed)