shared-credentials: Add auth.wikimedia.org to Wikimedia set

[Krinkle]

Overall Checklist

• I agree to the project's Developer Certificate of Origin
• The top-level JSON objects are sorted alphabetically
• There are no open pull requests for the same update

for shared-credentials.json

• There's evidence the domains are currently related (SSL certificates, DNS entries, valid links between sites, legal documents etc.)
• If using shared, the new group serves login pages on each of the included domains, and those login pages accept accounts from the others. (For example, we wouldn't use a shared association from google.co.il to google.com, because google.co.il redirects to accounts.google.com for sign in.)

Hi,

I'm an engineer on the MediaWiki Engineering team at Wikimedia Foundation. Over the next few months, we'll be moving logins from being local to each of ~900 wikis over ~10 top-level domains (with credentials shared behind the scenes) to instead happen centrally on the new auth.wikimedia.org domain.

This can be tested today on https://test.wikipedia.org/ where "Log in" directs you to https://auth.wikimedia.org/testwiki/wiki/Special:UserLogin. Compare this to the status quo on domains like en.wikipedia.org, wikidata.org, and ja.wikivoyage.org where login happens on the same domain.

Issue tracker: https://phabricator.wikimedia.org/T384844

[rmondello]

Hi @Krinkle! Thank you for this thoughtful contribution with lots of cited supporting evidence. Accommodating a change ahead of time isn’t something we’ve done before, but I’m more than happy to do it in this case.

[Krinkle]

@rmondello Thanks. Yeah, it's an atypical addition because it's not really adding a new site (i.e. a site with its own user signup and where community overlap to other sites might be minimal at first, so non-urgent). Anyone who's ever saved a password for Wikipedia will lose auto-fill unless the new domain is associated with previous domains.

[rmondello]

@Krinkle Atypical, but valuable!