warning in dev about missing turnstile property on CreateUserDialog

[hahn-kev]

Originally posted by @hahn-kev in #736 (comment)

we don't want to ignore this warning. 2 solutions that I liked were to either create a component that is specifically for switching turnstile off and on. Or just making it part of Form and making it optional.

[rmunn]

Discussed this with Tim at our last meeting and settled on making the MaybeProtectedForm component. This won't take long; PR coming soon.