[TASK] Add confirmation modal to delete a site configuration

Improve usability by adding a modal to require a second click.

Resolves: #85143
Releases: master
Change-Id: I310a655711aa730feca0b96e157c19eac8b7fcb0
Reviewed-on: https://review.typo3.org/57170


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>