feat: make authSessionOpener configurable

[bobbor]

Description of changes

This PR introduces a new option to the signInWithRedirect function.
The option is called authSessionOpener and allows customization on how to manage opening the authentication url for external identity providers.

Issue #, if available

#12895

Documentation PR
aws-amplify/docs#8376

Description of how you validated changes

In a sample app i have used external identity providers setup in my cognito configuration and overidden the URL handling using the new option, by opening a popup.

import { signInWithRedirect } from 'aws-amplify/auth';

await signInWithRedirect({
  provider: 'Google',
  options: {
    authSessionOpener: (url: string) => {
      window.open(url, "_blank", "popup")
    }
  }
});

Checklist

• PR description included
• yarn test passes
• Unit Tests are changed or added
• Relevant documentation is changed or added (and PR referenced)

Checklist for repo maintainers

• Verify E2E tests for existing workflows are working as expected or add E2E tests for newly added workflows

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.