[TASK] Add missing breaking.rst about service injection in validators

With #92238 the objectManager usage has been removed in Extbase
validationResolver. In the same patch it is also mentioned, that
validators must not have services injected. The possibility to
inject services in validators has been removed with #94451.

This change adds a breaking.rst document about the topic and
how to migrate existing code in extensions.

Resolves: #95026
Related: #92238
Releases: master
Change-Id: I139c21e9ddeeac1ef66af34090b1a5c0bbc097a8
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70811


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Benni Mack <benni@typo3.org>