Basic WorkerRun summary display on some ML results

Requires backend!1730 (merged), backend!1731 (merged), backend!1732 (merged), backend!1733 (merged), closes #994 (closed)

This implements WorkerRun display on elements, classifications, transcriptions and TranscriptionEntities only in the element details page. Only the summary field is displayed and follow-up issues need to be created to implement a dropdown to display more details, as well as support displays that simply cannot fit a whole summary, such as the metadata view.

I had to rewrite the grouping and sorting code and do some duplication on the templates to properly handle the complex sorting requirements. The classifications were left unsorted, only relying on the backend's sorting, so I added a sort by confidence descending then class name. The changes on transcription sorting close #1009 (closed).