Add option for new questions to be unlisted by default in Admin

[etflly]

Is your enhancement request related to a problem? Please describe

I want new questions to be initially unlisted by default. This differs from the review feature because questions in review cannot be answered. I want these unlisted questions to be answerable, specifically by administrators, allowing them to decide which questions should be made public.

Describe the solution you'd like

Provide an option in the Admin settings to make new questions unlisted by default.