Introduce a getActiveGlobalAndExtruderStacks method to ExtruderManager
Introduce a getActiveGlobalAndExtruderStacks method to ExtruderManager

It can be used to iterate over the active global and extruder stacks

Contributes to CURA-2006

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