This PR tries to address the 3 different startup scenarios for 1st layer calibration with the MMU:
- 1st lay cal started with correct filament already loaded in the nozzle - we should continue, but skip the first 58mm (first 2 g-codes in the hard coded sequence) of purge line extrusion
- 1st lay cal started with other filament already loaded in the nozzle - we should unload and then issue a toolchange with no extra unload
- 1st lay cal started without loaded filament - we should just do a toolchange with no extra unload
PFW-1457