[BUGFIX] Clarify Extbase exception message

Ensure that extension developers know where to look when
accessing an inaccessible action from a backend module.

Resolves: #88185
Releases: master, 9.5
Change-Id: I054a93b4162f5b3f2e1dafaf100ed3f9846e4df9
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64046


Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Alexander Schnitzler <git@alexanderschnitzler.de>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Alexander Schnitzler <git@alexanderschnitzler.de>
Reviewed-by: Benni Mack <benni@typo3.org>