[TASK] Add a PathUtility method to check for host-absolute URLs

This replaces a lot of string-based comparisons spread around
the code, which have been even wrong.
Having a single place for this kind of checks is beneficial.

The method is added to PathUtility as similar methods are already
present there.

Releases: master
Resolves: #95121
Change-Id: Ic73aac5d8c758dee5e0424bf2d54cd62b4b09e0c
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70913


Tested-by: core-ci <typo3@b13.com>
Tested-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>