[BUGFIX] Normalize slug before converting Unicode characters to ascii

This change adds a normalization for slug source before converting it
to ascii. This helps to avoid issues with various ways to encode the
same Unicode characters.

Used command:
   composer req symfony/polyfill-intl-normalizer

Resolves: #93764
Releases: master, 10.4
Change-Id: I9982fafd9c34c69bb6ca47ee8242f504b9974121
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/68492


Tested-by: core-ci <typo3@b13.com>
Tested-by: Daniel Goerz <daniel.goerz@posteo.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>