Previous this commit, failed messages widget data wasn't updated properly when you
set as reviewed/retry the last message displayed.
This commit resolve the problem and improves the "set as reviewed" action to avoid
multi-user inconsistencies (don't toggle the value).
- Any model inheriting from mail.thread will have a filter available to
obtain records with errors in their messages trackings.
- The messages can be marked as done to avoid false positives when the
issues are solved.
