Fault handling for organisation notification in case of email

**Signing**
If the user didn't specify an email for an organization, the organization might not have one registered in ER or kontaktregisteret (correct registers?). Currently, we don't notify the user or the service owner that anything went wrong if the email is not found and thus not sent. We only display the status of the message being sent to the Altinn Inbox or not.

With a new process engine, we can check correspondence for the status and thus update the user or service owner of this.

No files, tests, or entry points are named. The issue concerns organization email lookup and correspondence status in the new process engine; done should notify the user or service owner when an email is missing or sending fails, rather than showing only the Altinn Inbox status.

Written by the indexing model from the issue text.