Introduce center and multiply actions that work on the entire selection
Introduce center and multiply actions that work on the entire selection

Instead of working on a single object.

Contributes to CURA-3609

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