cubicweb-container #3589525 owned_by relation is not set for container entities during clone [validation pending]

Currently, entities created upon cloning of a container do not have anything in their owned_by relation.

priorityimportant
typebug
done in2.7.0
load0.100
load left0.000
closed by#ad6a74916d34 Clone: use the fastimport flush controller and .insert_entities
patchClone: use the fastimport flush controller and .insert_entities [applied]Add a test case for owned_by relation during clone [applied]