[BUGFIX] Prevent XSS in ViewHelpers

This patch removes wrongly introduced missing escaping in ViewHelpers
and adds some documentation about escaping settings.

Resolves: #75016
Releases: master
Change-Id: If0dbd8a5f7506a78238e6245b1a6f568ec7b3e27
Reviewed-on: https://review.typo3.org/47193


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Tested-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Reviewed-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Tested-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Reviewed-by: Michael Oehlhof <typo3@oehlhof.de>
Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Helmut Hummel <helmut.hummel@typo3.org>
Tested-by: Helmut Hummel <helmut.hummel@typo3.org>