[BUGFIX] Properly HTML encode site name in page module

Resolves: #84191
Releases: master, 8.7, 7.6
Change-Id: Id0f2da6f77b3c01293478329503dc922ccd7e72c
Reviewed-on: https://review.typo3.org/56087


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>