Allow hiding YOB

[tomudding]

What would you like?

(Without UI until GH-148)

Allow someone to set that they do not want their YOB to be shown to other members. Administrators and board members can still see it. External applications already work with an is 18+? model (however, it might still be necessary for activities, so we can introduce it there as well).

It is important to note that if you enable this option, you will also not see the YOB of other members.

Why is this needed?

No response

Other information

Related to GH-148.