Add virtual registry group sidebar nav item

What does this MR do and why?

Adds Virtual registry sidebar link for groups behind the feature flags ui_for_virtual_registries and maven_virtual_registry.

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Setup your local environment &15090 (closed)
2. Visit a group
3. Click Deploy sidebar menu item
4. Click Virtual registry menu item
5. Verify you were routed correctly

MR acceptance checklist

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Related to #525926 (closed)