FR (Authenticator): Customize Federated Auth / Social signin form

### On which framework/platform would you like to see this feature implemented?

Angular

### Which UI component is this feature-request for?

Authenticator

### Please describe your feature-request in detail.

One of the examples features social sign up and another example shows how to force users to agree to terms of service.
If you combine the two, social signup users dont have to agree to the terms and conditions. Is there a way to do this? Should this be handled through the signup prpviders?

### Please describe a solution you'd like.

Provide an opportunity to make a field required before the signup buttons for socials work.

### We love contributors! Is this something you'd be interested in working on?

- [ ] 👋 I may be able to implement this feature request.
- [ ] ⚠️ This feature might incur a breaking change.

Start by reviewing the Angular Authenticator's social sign-up flow alongside the terms-of-service example described in the issue. Determine where a required field can be checked before social sign-in, and consider the work complete when social signup is blocked until that field is satisfied.

Written by the indexing model from the issue text.