Also search through groups when figuring out the extruders of the selection
Also search through groups when figuring out the extruders of the selection

Contributes to CURA-3609

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