[TASK] Move Page Title generation to TSFE

The static method "PageGenerator::generatePageTitle()" only
operated on TSFE and is moved within the main controller,
which can be retriggered multiple times as before.

The same goes for TemplateService->printTitle().

Additionally, the method isAllowedLinkVarValue() is moved to TSFE
as well.

Resolves: #83254
Releases: master
Change-Id: If519963e33a57c21ac5cc575e4395444ab50450d
Reviewed-on: https://review.typo3.org/54973


Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>