[TASK] Modernize array function callbacks in GeneralUtility

Function callbacks are declared using the new PHP 8.1 feature
"first class callable", which e.g. uses the named `trim(...)`
function symbol, instead of the string `'trim'`.

see https://www.php.net/manual/en/functions.first_class_callable_syntax.php

Resolves: #100144
Releases: main
Change-Id: I708f86e022e397f3fcf32596043336b430e9c9ef
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78097


Reviewed-by: Oliver Bartsch <bo@cedev.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>