[!!!][TASK] Allow New Content Element override with custom module

Use a module / route to override the new content element
wizard instead of hard-coded paths to extensions, used
e.g. in templavoila.

Resolves: #70055
Releases: master
Change-Id: I648cbbde5dd024ace2d4189fadf434dc498d32f8
Reviewed-on: https://review.typo3.org/43417


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>