prod/atusb: separated flashing from testing; added enumeration and ID test
prod/atusb: separated flashing from testing; added enumeration and ID test

- atusb (flash, dfu): removed (to be handled by separate script)
- atusb (enumerate): implemented enumeration test
- atusb: enabled "identify", since the local anomaly has been solved

cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan