Filament Load and Unload button both runs the same gcode macro

[ongpujun]

Problem encountered : Pressing the unload button on the touchscreen extrudes filament instead of retracting.
Issue found: Load and Unload button runs the same gcode macro M604 on /src/event.cpp (line 3736, 3747) https://github.com/QIDITECH/QIDI_MAX3/blob/main/src/event.cpp
Correction request: M603 for filament unload and M604 for filament load as defined in printer.cfg

Thank you.