[TASK] Add modern typing to ArrayUtility

PHP 8.1's type system lets us add a lot more types
to ArrayUitlity's signatures, and remove some
unnecessary code in the process.

I also did a little bit of related modern-syntax
cleanup along the way, but this is mainly types.

That also lets us remove some now-unnecessary tests,
and with them some phpstan baseline entries.

Resolves: #97202
Releases: main
Change-Id: I05cd84524b42419a25ab06a9bffebcc2b90d9f6f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/73984


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>