[TASK] Make hreflang links absolute

Create absolute URL's for the hreflang links by using the configuration
of the current site.

Resolves: #86224
Releases: master
Change-Id: Id3196542875862b20145418956fcfdfcc3834241
Reviewed-on: https://review.typo3.org/58262


Reviewed-by: Kevin Appelt <kevin.appelt@icloud.com>
Tested-by: Kevin Appelt <kevin.appelt@icloud.com>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Jörg Bösche <typo3@joergboesche.de>
Reviewed-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Tested-by: Jigal van Hemert <jigal.van.hemert@typo3.org>