When a cloud printer is no longer received from mycloud, it is safe to
assume that the printer is removed from the account. In such a case,
the new function _devicesRemovedFromAccount(..) will retrieve all the
devices that are to be removed (i.e. they are added in Cura but they
do not exist in the clusters received from mycloud) and will remove
their output device. In addition the function will generate a message
that mentions all the devices that were no longer linked to the
account.
In order to achieve that, the Cloud/CloudOutputDeviceManager is
enriched with the dictionary self._um_cloud_printers that contains all
the currently existing cloud-enabled devices that were previously added
in Cura. In addition, the meta-data field "removed_from_account" is
added to all the cloud-enabled Cura devices to distinguish the ones
actually linked to the current account.
With these additions, the cloud devices that are removed from the
account will be automagically re-linked to it once the devices are once
again retrieved from mycloud for the specific account.
CURA-7438
ee7f2d4b38