[BUGFIX] Convert Node to DocumentFragment for modal consumption in EXT:dashboard

The patches #98164 and #98165 conflicted with each other as one made
the modal API stricter while the other populated the modal with a
soon-to-be invalid configuration. This currently breaks all subsequent
builds.

The modals received objects of type `Node` which are not consumable by
jQuery's `append()` method. To solve this issue, `Node` is now converted
to a `DocumentFragment`, which can be consumed by all involved parties.

Resolves: #98177
Related: #98164
Related: #98165
Releases: main
Change-Id: I4524b383e559d3b1342c0bf95e435caec6d36cc6
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/75517


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