How to configure your own "auto login" functionality using the OSF framework or JavaScript?

Summary: In the old framework, classic storefront, customers could create a login session by importing the CCRestClient module and then calling the login function like this CCRestClient.login(). How to achieve the same functionality in OSF?

Content (required): In classic storefront, customers could create a login session in a custom widget, adding as configuration a username and a password by importing the CCRestClient module and then calling the login function CCRestClient.login(). 

Version (include the version you are using, if applicable):22.2.2

Code Snippet (add any code snippets that support your topic, if applicable):

In classic storefront, start a login session using that username and password like this :