[BUGFIX] Ask user for notifications before requesting permissions

Since Firefox 72 a user interaction is required to prompt the user for native
browser notification permissions. This should prevent the user for
notification SPAM.

This patch introduces a modal confirmation, to get this user interaction.
The user is asked only once (as before), this is possible because the
modal is triggered only if a UC setting is not present.

Resolves: #90666
Releases: master, 9.5
Change-Id: I031a2addee9894db7e345f46d1e5e5d0d62316d6
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63567


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Susanne Moog <look@susi.dev>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Susanne Moog <look@susi.dev>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>