Refactor OTP authentication

[jan-tennert]

What kind of change does this PR introduce?

Feature

What is the current behavior?

You can sign in with an OTP like this:

supabase.auth.sendOtpTo(Email) {
    email = "example@email.com"
}

What is the new behavior?

You now do that with the new OTP AuthProvider:

supabase.auth.signInWith(OTP) {
    email = "example@email.com"
}