Improve ULS language search api

* Store prefixes and infixes separately in the data
* First match language code, then prefixes, then infixes
* Try to use suggestion either in user language or autonym first
* use formatversion=2 to avoid escaping Unicode

Using Language::fetchLanguageName might can have a small
performance impact. On the other hand there is now check
to skip languages we already found, avoiding some fuzzy
matching.

This is in a preparation for a change in jquery.uls to use
the search API more, while trying to reduce the amount of
weird autocompletion suggestions we show to the user.

Bug: T73891
Change-Id: Id94c5352d9a591969bf90144d1d2d5e758d08301

resources/js/ext.uls.mediawiki.js

@@ -23,7 +23,7 @@
 	// MediaWiki overrides for ULS defaults
 	$.fn.uls.defaults = $.extend( $.fn.uls.defaults, {
 		languages: mw.config.get( 'wgULSLanguages' ) || {},
-		searchAPI: mw.util.wikiScript( 'api' ) + '?action=languagesearch&format=json'
+		searchAPI: mw.util.wikiScript( 'api' ) + '?action=languagesearch&format=json&formatversion=2'
 	} );
 
 	// No need of IME in the ULS language search bar