[!!!][BUGFIX] Use decimal point of current locale

Let GeneralUtility::formatSize use the current locale's information
about number notation.

This also influences the stdWrap.bytes TypoScript property.

Resolves: #60152
Releases: master
Change-Id: I878fffc6f8e8dd038848dd8cd5d7fd3e7fa57f3d
Reviewed-on: http://review.typo3.org/33500
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Reviewed-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Tested-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Reviewed-by: Stefan Froemken <froemken@gmail.com>
Tested-by: Stefan Froemken <froemken@gmail.com>