[BUGFIX] Trim provided external URL in linkwizard modal

Avoid mistakes, especially by copy & paste, and trim the given data
before closing the modal and delegating the data.

Resolves: #98220
Releases: main, 11.5
Change-Id: Ie1a5670653fc28e16c54e1b7b1d1452a1e4f1917
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/75666


Tested-by: core-ci <typo3@b13.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>