Basic retraction info pages

[egonw]

Description

Uses information in Wikidata about retrations. The patch adds a /retraction/ landing page and provides a /retraction/Qxxx route for works known as retracted (screenshots below).

Several queries use the main or the scholarly WDQS explicitly, but I was not able to get all of them working yet.

Other features:

• link from /work/ to /retraction in the data table (if the article is retracted)
• on the landing page, list Wikidata items which use retracted articles as statement reference
• on the landing page, show the number of retractions per year

Caveats

It depends on the following data model: articles are P31-ed as retracted article. It also becomes a lot more useful if that statement has a 'start time' qualifier (which 90% will have, pending a few QS batches).

Check any of the following which apply:

• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
  • I have made corresponding changes to the documentation
• This change requires new dependencies (please list)

If you make changes to the Python code

• My code passes the tox check, I can receive warnings about tests, documentation or both

Testing

• A new landing: http://127.0.0.1:8100/retraction/
• A retracted article: http://127.0.0.1:8100/retraction/Q34377294

Checklist

• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have not used code from external sources without attribution
• I have considered accessibility in my implementation
• There are no remaining debug statements (print, console.log, ...)

Screenshots

/retraction/Qxxx aspect

/retraction/ landing page

/retraction/ landing page: bar plot "per year"

panels showing Wikidata statements citing retracted articles

/retraction/Qxxx aspect's "data" panel

[egonw]

Note to self: requested query help here