SITL: add Omni3Mecanum vehicle to SIM_Rover #31770

Job	Run time
build (chibios, Durandal)	17m 6s
build (chibios, MatekF405)	15m 0s
build (chibios, KakuteF7)	15m 59s
build (chibios, MatekH743-bdshot)	11m 55s
build (chibios, Pixhawk1-1M)	17m 51s
build (chibios, MatekF405-CAN)	4m 0s
build (chibios, DrotekP3Pro)	3m 48s
build (chibios, Hitec-Airspeed)	5m 9s
build (chibios, f103-GPS)	4m 10s
build (disco, armhf)	8m 7s
	1h 43m 5s

Provide feedback