Purpose of this commit is to use the newly introduced feature to log a message
when adding or removing an entry in block list of emails in email marketing
application.
Logging itself is improved, as it now contains
* source of the request (unsubscribe link, or manual ask through the portal
unsubscription page);
* link to the source mailing;
* link to the document that generated the click (a mailing contact, a sales
order, ...);
Task-2710804 (Mail: Clean MailThread API)
Prepares Task-2150462 (Mass Mailing: Unsubscribe flow refactoring)
Part-of: odoo/odoo#106568