[BUGFIX] Fix Undefined array key "rootLevel" on import/preview

Fixes exception in impexp when an extension does not have a
value for TCA[tableName][ctrl][rootLevel]

Resolves: #104308
Releases: main, 12.4, 11.5
Change-Id: Ia2b8095c35ba6b07827525a65e0dcbb6fa1d060e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/85104


Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Garvin Hicking <gh@faktor-e.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Guido Schmechel <guido.schmechel@brandung.de>
Tested-by: Garvin Hicking <gh@faktor-e.de>