Provide `hasScopedLabelsFeature` to the new Vue MR list page

What does this MR do and why?

For one part of #504362 (closed)

The MR list page supports scoped labels, but the feature availability is not provided to the page.

This sends the feature availability to the front end.

References

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MR acceptance checklist

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Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Enable and create a scoped label
2. Assign the label to an MR
3. Go to the MRs list