[BUGFIX] Use parent's module icon as fallback for shortcuts

If no icon is provided for submodule, use a fallback to the icon of the
parent module instead of directly using the empty-empty icon.

Resolves: #103904
Releases: main, 12.4
Change-Id: I4e989483880fd88df904e9028f1d2cf6cd5c29f7
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84390


Tested-by: Riccardo De Contardi <erredeco@gmail.com>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Garvin Hicking <gh@faktor-e.de>
Reviewed-by: Garvin Hicking <gh@faktor-e.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>