Add status column to Secrets table

What does this MR do and why?

Implements #470459.

This adds the status column to the index page for Secrets Management. Note that there is no backend integration available, so this MR relies on mock data.

MR acceptance checklist

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Before	After

How to set up and validate locally

1. Enable the feature flag for Secrets Management.

   Feature.enable(:ci_tanukey_ui)

2. Visit the Secrets page for your project e.g. <path-to-project>/-/secrets
3. Verify that the status column exists for the table.