Fix the Q&A when used with new facet links.
Fix the Q&A when used with new facet links.

The Q&A now uses FacetExtractor to get the facets.

This means it can handle facets nested as follows:

links -> facet_groups -> links -> facets -> links -> facet_values

alphagov/finder-frontend,alphagov/finder-frontend,alphagov/finder-frontend,alphagov/finder-frontend