New board: FlyFishRCF405

[github-actions]

ArduPilot has a hwdef for FlyFishRCF405 (chibios) that fcPicker does not yet carry.

• Platform: chibios
• MCU: STM32F405xx
• Flash: 1024 KB
• hwdef: https://github.com/ArduPilot/ardupilot/tree/master/libraries/AP_HAL_ChibiOS/hwdef/FlyFishRCF405

To import: run .venv/bin/python tools/build.py against an ArduPilot checkout containing this board, then commit the generated data/boards/FlyFishRCF405.json.