[TASK] Suggest PHP "intl" extension

This is the basis for further improvements, which require
locale aware operations.

Resolves: #83171
Releases: master
Change-Id: Iae9bf29b88031a0115cdf3dfb2957c97c9cc0c34
Reviewed-on: https://review.typo3.org/54878


Reviewed-by: Mathias Brodala <mbrodala@pagemachine.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Andreas Wolf <andreas.wolf@typo3.org>
Tested-by: Andreas Wolf <andreas.wolf@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>