[TASK] Omit header "content elements" in linkbrowser if no elements

available

If no content elements are available to be linked to, the header should
not be rendered at all.

Resolves: #99228
Releases: main
Change-Id: I14b38de415dcb70f7e6c44570a8f442372e3eaed
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76863


Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Josef Glatz <josefglatz@gmail.com>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Josef Glatz <josefglatz@gmail.com>
Reviewed-by: Oliver Bartsch <bo@cedev.de>