DroneCAN/UAVCAN Menu, Update should support .hex files for AM32 DroneCAN ESCs

[rmackay9]

ArduPilot has support the AM32 DroneCAN ESCs for about a year and I've noticed that it is not possible to use Mission Planner's DroneCAN/UAVCAN screen to update the firmware because:

• the am32 firmware site (https://am32.ca/downloads) only provides .hex files
• MP's Update screen only supports .apj or .bin files

By the way, I did try just uploading the .hex but it resulted in the ESCs becoming unuable with messages including "bad eeprom header" and "no app signature" and I had to reload the bootloader

FYI @Huibean

[Huibean]

@rmackay9 .hex format now support on dronecan webtools