Disable Sign Up config option for Internal Apps/Services?

I was wondering if/when this project will include the disable sign up config from [v4.8.0](https://github.com/firebase/firebaseui-web/releases/tag/v4.8.0) of firebaseui-web for [configuring the email provider](https://github.com/firebase/firebaseui-web#configure-email-provider)?

I feel like this would be a necessary option to have for this project as it is needed for internal web services and would love to be able to tap into this feature while keeping it all in react.