[BUGFIX] Add support for t3:// syntax to FileCollector

FileCollector::addFilesFromFolder now supports the t3://folder URN as
identifier for a folder. This allows the FILES cObj and the
FilesProcessor data processing to use that syntax.

Resolves: #82627
Releases: master, 8.7
Change-Id: I31376169f5868c6f7c52cf2b6ca98fe41bb1e111
Reviewed-on: https://review.typo3.org/54250


Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Frans Saris <franssaris@gmail.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Joerg Boesche <typo3@joergboesche.de>
Tested-by: Benni Mack <benni@typo3.org>