[Data rearchitecture] Implement UpdateWikidataStatsTimeslice

[gabina]

What this PR does

This PR creates a new UpdateWikidataStatsTimeslice class (based on the existing UpdateWikidataStats) to import wikidata stats through the wikidata-diff-analyzer gem and create course_stats rows for courses using wikidata, without using Revisions table.

Revisions behavior:

As part of the daily update, we call import_wikidata_summaries (only for wiki education dashboard), which imports Wikidata revision summaries through the WikidataSummaryImporter.

On the other hand, as part of the UpdateCourseStats class, we call update_wikidata_stats, which invokes UpdateWikidataStats class. It has two main tasks:

• It updates the summary field for revisions without summary through the WikidataDiffAnalyzer gem.
• and updates course_stats table through the UpdateWikidataStats class.

This indicates a combination of revisions: some containing statistics from the WikidataSummaryImporter, and others derived from the WikidataDiffAnalyzer gem.

Timeslices behavior:

In the timeslice-based approach, the daily update does not generate any revision summaries because the Revisions table contains no entries. Instead, statistics for revisions are fetched dynamically using the WikidataDiffAnalyzer gem when revisions are loaded into RAM.
To store the (partial) Wikidata statistics, we introduced a stats field in the CourseWikiTimeslice model. This field is used to save the Wikidata statistics for a specific timeslice. Once statistics for individual timeslices are available, course-level statistics can be calculated by aggregating them.

Screenshots

Stats using revisions version:

Stats using timeslices version:

Open questions and concerns

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