Add-on Force people to Register & Login with Steam

Remove the option for people to register with email and password. And force members to register or sign in with their Steam Account. I require this because it's a rather smart idea to prevent people from stealing account details and logging in with it. This would add another layer of protection because they would be forced to log in with Steam. My point is that I don't want to make it optional to log in with Steam. What I'm interested in is forcing people to do it.

XF: 1.5.9