Make raft middle thickness warn based on nozzle size
Make raft middle thickness warn based on nozzle size

Whether the layer is too thick to extrude properly depends on the nozzle size, not on the line width.

Contributes to issue CURA-3650.

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