To allow tighter cooperation with the printer - after the printer thinks it unloaded the filament from the drive gear,
we'll still rotate the drive gear as long as the MMU reports progress state UnloadingFromFSensor.
After those 40mm of slow unload distance, the MMU checks the fsensor (like is has been doing before).
If FSensor is off at this moment, everything is fine a the unload will continue at full speed.
This solves a number of issues - if FINDA or FSensor failed,
the unload was never "complete" - filament was stuck in the selector
blocking it from normal operation.
Now, after all errors have been resolved, filament is explicitly FED
into FINDA and then RETRACTED to Pulley.