Move new_id in ContainerManager::duplicate into a general block
Move new_id in ContainerManager::duplicate into a general block

Saves duplication

Contributes to CURA-2006

totalretribution/Cura,ynotstartups/Wanhao,hmflash/Cura,hmflash/Cura,ynotstartups/Wanhao,Curahelper/Cura,fieldOfView/Cura,senttech/Cura,totalretribution/Cura,fieldOfView/Cura,Curahelper/Cura,senttech/Cura