[BUGFIX] Avoid PHP warning in ArrayUtility::getValueByPath()

Children of $array in ArrayUtility::getValueByPath() may contain other
datatypes than array, therefore check the datatype by is_array()
before calling array_key_exists() in order to avoid a PHP warning.

Resolves: #90241
Releases: master, 9.5, 8.7
Change-Id: Ibde8f854a28a0aef68ed33ed172299cb4e1ff2ca
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63066


Reviewed-by: Stephan Großberndt <stephan.grossberndt@typo3.org>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Benjamin Franzke <bfr@qbus.de>