[FEATURE] Introduce PSR-14 event to define whether files are selectable

This introduces a new PSR-14 event, enabling
extension authors to define whether a file
can be selected in the file browser. This was
previously only possible by cross classing the
FileBrowser class.

Resolves: #99118
Releases: main
Change-Id: I6fda270b86e8a9d2637c6af31c5fcd83238d9a1a
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76663


Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Oliver Bartsch <bo@cedev.de>