Create single form fetching endpoint

[ks129]

• Created custom dict function for Form model to return only public fields when user is not admin.
• Return only public fields for discovery.
• Move form creation to /forms POST from /forms/new.
• Created route for getting single form that return all fields and all forms for admins, but only public fields and open forms for others.
• Closes Add route for returning a form #20

[jb3]

The changing of /new to / is incorrect here. We should delete the new file entirely and instead add a new post method to the route at backend/routes/forms/index.py

[jb3]

One more minor thing