Add simulated GPIO ("board") LEDs. #31546

Job	Run time
build (chibios, Durandal)	26m 19s
build (chibios, MatekF405)	23m 1s
build (chibios, KakuteF7)	21m 46s
build (chibios, MatekH743-bdshot)	23m 57s
build (chibios, Pixhawk1-1M)	23m 2s
build (chibios, MatekF405-CAN)	3m 59s
build (chibios, DrotekP3Pro)	4m 41s
build (chibios, Hitec-Airspeed)	5m 57s
build (chibios, f103-GPS)	6m 11s
build (disco, armhf)	15m 41s
	2h 34m 34s

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