Returns the login URL for sites that use Wix as their identity provider.
Use this function when your site uses a Wix login page
to handle member authentication. Wix manages the login experience and redirects the member back to your site after authentication.
The returned URL points to the /api/auth/login route.
The URL to redirect to after login.
This method doesn't return any custom errors, but may return standard errors. Learn more about standard Wix errors.