[BUGFIX] Catch FolderDoesNotExistsException in linkvalidator

Catch FolderDoesNotExistsException in linkvalidators checklink method,
if wrong links like file:// checked.

Resolves: #84488
Releases: master, 8.7

Change-Id: Ife1e34a638a56379fcc0fde7150c945c93a6157a
Reviewed-on: https://review.typo3.org/56385


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Tested-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>