Add get_airspeed method to lua bindings #33128

Job	Run time
build (chibios, Durandal)	15m 49s
build (chibios, MatekF405)	15m 2s
build (chibios, KakuteF7)	15m 45s
build (chibios, MatekH743-bdshot)	15m 16s
build (chibios, Pixhawk1-1M)	17m 52s
build (chibios, MatekF405-CAN)	3m 53s
build (chibios, DrotekP3Pro)	4m 29s
build (chibios, Hitec-Airspeed)	5m 16s
build (chibios, f103-GPS)	5m 44s
build (disco, armhf)	13m 57s
	1h 53m 3s

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