Bump mediawiki-codesniffer to ^52 to unblock Composer

[JeroenDeDauw]

Composer refuses to install the phpcs 3.6.2 that codesniffer 39.0.0 pins, because of advisory
PKSA-rdkp-vv9z-mjkg. Only the Code style and PHPStan jobs were affected, as they are the ones
running Composer inside the extension directory. Codesniffer 52 needs PHP 8.3 and the plugin
that registers PHPCSExtra.

Of the new findings, five sniffs are excluded, each mirroring an exclusion already in phpcs.xml:
Squiz.ControlStructures.ControlSignature.SpaceAfterCloseBrace (12),
Generic.CodeAnalysis.AssignmentInCondition (11), Universal.WhiteSpace.CommaSpacing (8),
Squiz.WhiteSpace.FunctionOpeningBraceSpace.SpacingAfter (3) and
MediaWiki.WhiteSpace.SpaceAfterClosure.NoWhitespaceAfterArrow (2). Two are fixed in tests: an
implicit nullable parameter type and an assertEquals over two counts. phpcs no longer sniffs
JavaScript, where its tokenizer misreads the nesting in JQueryLeafletTest.js.

_{AI-authored — Claude Code, Opus 5 (max); detailed spec from @JeroenDeDauw, no redirections; diff not yet human-reviewed; phpcs run to green locally against a PHP 8.3-pinned install, everything else on CI.}