Complete social auth flow.

[rusher2004]

So far, only the email sign up and sign in flow is completed. To be complete, the social signup/in needs to do the following:

1. On signup, SuperTokens will redirect the user to /auth/callback/{provider}.
   • The web client needs to create this view
   • The view should present a form for the user to provide their first name, last name, and desired username.
   • The form will update the user info using the PUT /user/{username} endpoint
2. On success, redirect to home page.