[BUGFIX] Expose ContextHelp module url to JavaScript

Resolves: #90490
Releases: master
Change-Id: Idc9c1d2fb2990116933e6cc0e1700daa46778847
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63373


Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>