[TASK] Add test for checkValueForSelect

According to a report, items added by
itemsProcFunc cannot be saved via
datahandler. Adding a test case to test
the behaviour.

Resolves: #76509
Releases: master
Change-Id: I2d5e34c6a9eff7a8fa0129106c9676307c5e3151
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63917


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Susanne Moog <look@susi.dev>
Reviewed-by: Susanne Moog <look@susi.dev>