Search result localization and "boosting"

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For cases where the selected interface language has been explicitly selected, we could have that selection change show search queries are ranked and displayed. For example, documents in the selected language could be "boosted" to appear higher in the search results, and we could swap the title / original_title display order in some cases.

Off the top of my head, some things this would involve:

• include language filter as a "boost" in elasticsearch query (along with existing boosts) to impact sorting when appropriate
• conditional logic for title display preference (probably jinja2 macro)
• possibly a query filter, parameter, or some other indication that this change is happening and a way to opt-out
• testing of these changes for performance, search quality, and user experience
• documentation ("help") updates to describe this change