[!!!][TASK] Drop TSFE->dtdAllowsFrames

The typolink calculation for checking of allowing frames has been encapsulated
in the TypoLinkBuilder extraction, so this public property is also obsolete.

Resolves: #81198
Releases: master
Change-Id: Ic2d0e64a754da983abfd6c9bcaa66884eaa9af35
Reviewed-on: https://review.typo3.org/52782


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>