[BUGFIX] Implement Tag interface for DocBlock tags

Since phpdocumentor/reflection-docbloc 5.2.x a tag is required to
implement also the phpDocumentor\Reflection\DocBlock\Tags\Formatter\Tag
interface.

This patch implements the tag interface for the Null_ tag defined in
Extbase.

Resolves: #91832
Releases: master, 10.4
Change-Id: Idb836dc3f8816a5c2c40d429a61dcda1cd27fd7f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/65061


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Nicole Cordes <typo3@cordes.co>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Nicole Cordes <typo3@cordes.co>
Reviewed-by: Benni Mack <benni@typo3.org>