[TASK] Add empty extension compatibility6

This is a placeholder extension taking deprecated functionality
into child care to prolong the adaption phase for updating
individuals.
After all function have been moved, this extension will
be released to TER and removed from TYPO3 CMS core.

Change-Id: I8df0ecefcebdf3f2fe304529e6a79065254dee8e
Resolves: #62014
Relates: #62013
Releases: master
Reviewed-on: http://review.typo3.org/33127
Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>