AP_Mount: added sending of attitude and velocity for SIYI #3353

Job	Run time
build (stm32f7, chibios, 10)	20m 30s
build (stm32h7, chibios, 10)	18m 28s
build (fmuv2-plane, chibios, 10)	11m 14s
build (periph-build, chibios, 10)	39m 25s
build (iofirmware, chibios, 10)	4m 38s
build (CubeOrange-bootloader, chibios, 10)	1m 35s
build (fmuv3-bootloader, chibios, 10)	1m 25s
build (revo-bootloader, chibios, 10)	2m 0s
build (stm32h7-debug, chibios, 10)	9m 54s
build (fmuv3, chibios, 10)	18m 13s
build (revo-mini, chibios, 10)	17m 31s
build (MatekF405-Wing, chibios, 10)	17m 7s
build (CubeOrange-ODID, chibios, 10)	16m 44s
build (CubeRedPrimary-bootloader, chibios, 10)	1m 31s
build (configure-all, chibios, 10)	14m 12s
build (build-options-defaults-test, chibios, 10)	31m 24s
build (signing, chibios, 10)	16m 13s
	4h 2m 4s

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