AP_NavEKF3: add an option_is_enabled method #43299

Job	Run time
build (stm32f7, chibios, 10)	9m 38s
build (stm32h7, chibios, 10)	8m 36s
build (fmuv2-plane, chibios, 10)	5m 6s
build (periph-build, chibios, 10)	7m 47s
build (iofirmware, chibios, 10)	3m 47s
build (CubeOrange-bootloader, chibios, 10)	2m 58s
build (fmuv3-bootloader, chibios, 10)	2m 57s
build (revo-bootloader, chibios, 10)	2m 57s
build (stm32h7-debug, chibios, 10)	5m 54s
build (fmuv3, chibios, 10)	11m 59s
build (revo-mini, chibios, 10)	10m 1s
build (MatekF405-Wing, chibios, 10)	10m 17s
build (CubeOrange-ODID, chibios, 10)	7m 26s
build (CubeRedPrimary-bootloader, chibios, 10)	3m 21s
build (configure-all, chibios, 10)	13m 8s
build (build-options-defaults-test, chibios, 10)	16m 47s
build (signing, chibios, 10)	6m 37s
build (CubeOrange-PPP, chibios, 10)	5m 49s
build (CubeRed-EKF2, chibios, 10)	6m 7s
build (SOHW, chibios, 10)	8m 15s
build (Pixhawk6X-PPPGW, chibios, 10)	3m 54s
build (new-check, chibios, 10)	11m 14s
	2h 44m 35s

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