[BUGFIX] Download link for absolute file path

Support FAL adapters that return absolute urls as public file url

Change-Id: I68f2675a1a5137e6d0c5cadee7b21e82e8730fdf
Resolves: #56659
Releases: 6.2
Reviewed-on: https://review.typo3.org/28168
Reviewed-by: Wouter Wolters
Reviewed-by: Christian Weiske
Tested-by: Christian Weiske
Reviewed-by: Frans Saris
Tested-by: Frans Saris