[BUGFIX] Fix missing getter/setter tests

Creates getter/setter tests for 1:1 and n:1 relations
and properties of type \DateTime.

Change-Id: I8f68c4cb1511b5817730ef3276bf0b049238a7ae
Resolves: #54713
Reviewed-on: https://review.typo3.org/26622
Reviewed-by: Nico de Haen
Tested-by: Nico de Haen