Double opt-out for unsubscribe

Problem/Motivation

Subscribe supports a double‑opt‑in confirmation flow: when a user chooses to subscribe, an email is sent with a per‑recipient link that redirects to the site’s confirmation page. However, unsubscribe does not have an equivalent “double‑opt‑out” in the Webform Simplenews handler; when a user unsubscribes via Webform, the handler does not send a verification email with a per‑recipient link - instead, the unsubscribe is applied immediately.

Related behavior: the unsubscribe token [simplenews-subscriber:unsubscribe-url] resolves only in Simplenews newsletter-related emails and is not generated for a Webform‑triggered unsubscribe action.

Steps to reproduce

1. Set up a Webform with an email field.
2. Add a Webform Simplenews handler to subscribe the address to the default newsletter.
3. Add another handler to unsubscribe the same way (using changes from MR #10 for unsubscribe).
4. Submit the form.
5. Observed: subscribe has a confirmation step; unsubscribe does not (no verified link is sent via the handler).

Setup

• Drupal: 10.3
• Webform: 6.2.9
• Simplenews: 4.1.0
• Webform Simplenews Handler: 2.0.4 (using changes from MR #10 for unsubscribe)

Proposed resolution

Add a handler option for “Verified unsubscribe (send link)” so the handler emails the per‑recipient hashed unsubscribe URL instead of removing immediately.