[commhistory-daemon] Show notifications for MMS errors

A notification should be shown any time a MMS event goes from an "active"
state to an "inactive" one. This adds notifications for MMS transfer errors
and cases where a manual download is required.

These notifications behave like and are grouped with other MMS related
notifications.

No notifications are shown for cases where there's no associated event.
Generally, that means catastrophic database failure.