[BUGFIX] Fix PHPDoc of ButtonProvider

Resolves: #91112
Releases: master
Change-Id: I6fef3f196afd44a11fbd5d688bec45457a28aad6
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64231


Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Richard Haeser <richard@maxserv.com>
Reviewed-by: Alexander Schnitzler <git@alexanderschnitzler.de>
Reviewed-by: Christian Eßl <indy.essl@gmail.com>
Tested-by: Richard Haeser <richard@maxserv.com>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Alexander Schnitzler <git@alexanderschnitzler.de>
Tested-by: Christian Eßl <indy.essl@gmail.com>