Add pageCount to crawls and uploads and use in frontend for page counts

[tw4l]

Fixes #2257

This is a follow-up to the public collections work, which adds pages to the database for uploads. All crawls and uploads now have a pageCount field which is populated when the item is successfully added. A new migration is also added to populate the field for existing archived items that don't have it set yet.

OrgMetrics have also been modified to include crawlPageCount and uploadPageCount, and to include the total of both in pageCount, and all three included in the frontend org dashboard.

The frontend has been updated to use pageCount rather than stats.done wherever appropriate, meaning that in archived item lists and details we now have a consistent page count for both crawls and uploads.

Screenshots

Org Dashboard

Archived Items list

Crawl Detail

Upload Detail

Collection Archived Items List

Testing

(Requires having both backend and frontend deployed from this branch)

New functionality

• Deploy this branch
• Create new crawls and uploads and verify that page count appears correctly throughout the frontend for all new crawls and uploads

Migration

• Deploy from latest main
• Create some crawls and uploads
• Change to this branch and re-deploy
• Verify migration ran without errors in backend logs
• Verify that page count has been populated successfully by checking archived items lists, crawl and upload detail pages, and dashboard to ensure there are no longer any missing page counts.

[emma-sg]

Nice, looks good!