Extension:InterwikiMap/Data

What data should the InterwikiMap API module provide upon request, and possibly use in filters for determining what interwiki prefixes to include in the interwiki table (using recursive AND, OR, XOR, and NOT tests similar to what is found in Autopromote.php)? Ideas:
 * Data for the interwiki table fields:
 * ✅ iw_prefix
 * ✅ iw_url
 * iw_api: Shouldn't be too hard to get; we need this to poll those 20,000 APIs for extra data anyway
 * iw_wikiid: I'm not too familiar with this, but I assume it's unnecessary and probably unavailable in many cases; it's sensitive
 * iw_local: I'm not sure how to make the decision of what settings to use for this
 * iw_trans: I'm not sure how to make the decision of what settings to use for this
 * Data from wikiindex:Template:Wiki, including:
 * name: Available through meta=siteinfo
 * logo: May as well make this available through ApiQuerySiteinfoEnhanced, so that wiki index bots can more easily get it. Use $wgLogo
 * wide logo: There might be a way to test for this and get that data.
 * recentchanges URL: Make available through ApiQuerySiteinfoEnhanced
 * wikinode URL: These never really caught on, but we may as well make it an available option, either through an optional configuration setting or (probably preferably) through a MediaWiki:Wikinode-url page.
 * status: Use Wikiindex's assessment. Pretty important data; if the site is dead, people probably don't want it on their interwiki prefix list.
 * language: Make available through ApiQuerySiteinfoEnhanced; it's config setting $wgLanguageCode
 * editmode: Can probably be discerned from config settings; see Manual:Preventing access. Or we can use Wikiindex's data.
 * engine: Shouldn't be too hard to detect by polling the wiki; also available from Wikiindex.
 * license: Available from siprop=general
 * maintopic: There should probably be a MediaWiki:Maintopic system message. Of course, there can be an "official" main topic and what outsiders (e.g. Wikiindex) assess it as being. Maybe both should be provided.
 * backupurl: Found at '/Special:Statistics' on Wikia sites. This should be another system message, probably.
 * backupdate: This should be another system message, probably.
 * pages: siprop=statistics
 * statistics URL: Shouldn't be too hard to get, by similar means at RecentChanges
 * wikiFactor = From Wikiindex.
 * wikiFactor URL = From Wikiindex, or get from Special:PopularPages, if it's available
 * All the data from meta=siteinfo
 * siprop=extensions: pretty useful for generating extension usage info at MediaWiki.org
 * Any other siprop=statistics data: articles, edits, images, users, activeusers, admins, jobs. It should also say how "activeusers" is defined.
 * siprop=namespaces: could provide some interesting namespace ideas. Some wikis might have massive numbers of namespaces, though; we'll have to check on that.
 * Other
 * url for this wiki's about page. Should probably be a system message.
 * url for this wiki's wikiindex entry. Get from wikiindex through a reverse lookup.