Log in a user using magiclink or a one-time password (OTP).
Requires either an email or phone number.
This method is used for passwordless sign-ins where a OTP is sent to the user's email or phone number.
If the user doesn't exist, signInWithOtp() will signup the user instead. To restrict this behavior, you can set shouldCreateUser in SignInWithPasswordlessCredentials.options to false.
If you're using an email, you can configure whether you want the user to receive a magiclink or a OTP.
If you're using phone, you can configure whether you want the user to receive a OTP.
The magic link's destination URL is determined by the SITE_URL.
Magic links and OTPs share the same implementation. To send users a one-time code instead of a magic link, modify the magic link email template to include \{\{ .Token \}\} instead of \{\{ .ConfirmationURL \}\}.