Disallow Foreign Key Arrays in the UI

[Array of foreign keys]( are not supported by supabase; and are not planned as I see.

As in #535 the suggestion method is to create junction tables instead.

In the FE UI after I define a foreign key relation, I would like the define as array option to be disabled with some help text added. See screenshot.

![Screenshot 2024-01-30 at 13 04 20](

This is a quick and easy task; and would save some dramatic time!