[BUGFIX] Allow multi-byte characters in live search

Resolves: #83539
Releases: master, 8.7
Change-Id: I4d589d0654ab7ee091b664957fbb8c6d101be663
Reviewed-on: https://review.typo3.org/55997


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Guido Schmechel <littlegee@web.de>
Tested-by: Guido Schmechel <littlegee@web.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Tested-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>