[TASK] Filelist: Renaming: Add a better flash message

Just add another/meaningful message to the flash message
queue if the file/folder was not really renamed. It just gives a
better feedback to the backend user.

Resolves: #79206
Releases: master
Change-Id: Id2378fdd0f24a94c2260cff9fd7e2cb8feb40eaf
Reviewed-on: https://review.typo3.org/51203


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Frans Saris <franssaris@gmail.com>
Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Mona Muzaffar <mona.muzaffar@gmx.de>
Tested-by: Frans Saris <franssaris@gmail.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>