[BUGFIX] EM must treat line breaks correctly in extension data

The XML push-parser now correctly collects the data for
description and upload comment. When the data contain line breaks
the characterData() method is called multiple times
for each line of data.

Resolves: #78306
Releases: master, 7.6
Change-Id: Ibfa446b92904572d1f4530b265e94228857a5f02
Reviewed-on: https://review.typo3.org/50516


Reviewed-by: Nicole Cordes <typo3@cordes.co>
Tested-by: Nicole Cordes <typo3@cordes.co>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>