[TASK] Migrate PATH_site usages to Environment API - Part 1

Use Environment::getPublicPath() and Environment::getProjectPath()
respectively, depending on the use-case instead of PATH_site.

Resolves: #85259
Releases: master
Change-Id: I7debc10332232f3b8a29c9b8def268f389d71b88
Reviewed-on: https://review.typo3.org/57163


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>