SecurePoll: Unauthorized access to SetTranslationHandler allows arbitrary text changes

SetTranslationHandler.php does not validate that the user is an election admin, allowing any (even unauthenticated) user to change election-related translation text. While partially broken in newer MediaWiki versions, the check is still missing. This issue affects Mediawiki - SecurePoll extension: from 1.39.X before 1.39.13, from 1.42.X before 1.42.7, from 1.43.X before 1.43.2.