Handle duplicate resources

[rtibbles]

Summary

• Adds utility function for deduplicating arrays of ContentNodes by content_id
• Groups together and then adds a copies property to the ContentNodes with all of the nodes therein
• Uses currently activated language code in an attempt to surface the most relevant node to the user out of the duplicates
• Uses this in both search results and resumable content node display

References

Fixes #8700
Fixes #8498

Reviewer guidance

Does the styling and placement of everything look correct?

Flagging that this does produce slightly unpredictable counts of search results due to the deduplication, but I think it is still preferable to displaying the duplicates, especially in restricted searches.

Resume duplicates

Search duplicates (failure to render is because I don't actually have the exercise imported locally)

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Testing checklist

• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
• Critical user journeys are covered by Gherkin stories
• Critical and brittle code paths are covered by unit tests

PR process

• PR has the correct target branch and milestone
• PR has 'needs review' or 'work-in-progress' label
• If PR is ready for review, a reviewer has been added. (Don't use 'Assignees')
• If this is an important user-facing change, PR or related issue has a 'changelog' label
• If this includes an internal dependency change, a link to the diff is provided

Reviewer checklist

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
• Contributor is in AUTHORS.md

[radinamatic]

produce slightly unpredictable counts of search results due to the deduplication, but I think it is still preferable to displaying the duplicates, especially in restricted searches.

💯 ✖️ 💯

Manual testing passes, I'm not able to see duplicates in 'Home' or 'Library > Recent'! 👍🏽

[radinamatic]

👏🏽