[TASK] Group search result items again

With the refactoring of the backend search, the result grouping got
lost. This patch adds the grouping again.

Resolves: #99116
Releases: main
Change-Id: I94f09377c66b3b8465130af89329806b9e242d86
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76660


Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Susanne Moog <look@susi.dev>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Susanne Moog <look@susi.dev>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>