[BUGFIX] Make Notifications module usable in install tool

This patch makes the Notification module in standalone install tool
usable by adding the required CSS and fixing the dependency
to the global TYPO3 object, which only exist in backend context.

Resolves: #82138
Releases: master
Change-Id: I954324e9d19569eedb1eb5e0ecfaf821fcecb070
Reviewed-on: https://review.typo3.org/53760


Reviewed-by: Mona Muzaffar <mona.muzaffar@gmx.de>
Tested-by: Mona Muzaffar <mona.muzaffar@gmx.de>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>