SelectMany property doesn't work correctly when SelectItem.Value contains comma characters

Description

Properties that use the SelectManyAttribute and get the values from a ISelectionFactory doesnt handle values that contains the character comma (,). The underlying storage uses that character to separate values from each other and therefor values including commas cannot be properly saved to the database. A fix was realesed that used JSON to handle the issue and while it worked correctly it was a breaking change, CMS-26903, that needed to be reverted. This new issue is a clone of the original CMS-23405 in order to find a different solution to the problem.