- include icm20948 on most boards by default
- create more test variants for default boards near flash limit (cuav_nora_test, cuav_x7pro_test, holybro_durandal-v1_test)
- new IMU driver structure with state machine (no sleeps in bus thread)
- verify all configured registers and trigger reset on failure
- detect if DIO1 or DIO2 are actually connected for data ready interrupt usage
- don't use CRC-16 on burst transfers except for verified lots
- fmu-v5 debug and stackcheck builds now need to be CONSTRAINED_FLASH to fit
- delete unused holybro_durandal-v1_stackcheck build (also CONSTRAINED_FLASH)