Magnetometer support in sfusion

[furrycoding]

Added magnetometer support for sfusion sensors
Currently, only LSM6DSR with QMC5883L via sensor hub is supported (LSM6DSO might work, DSV probably won't since I didn't even look at the datasheet lol)

Sensors that support magnetometers receive a driver for it as a template argument. That driver is structured pretty much like a normal sfusion driver. Later I want to also add an option to pass it directly to SoftFusionSensor (for mags that are directly connected to the main I2C bus)

TODO:

• Add axis remapping
• Support mag driver passed directly to SoftFusionSensor
• Check the registers and test LSM6DSO/DSV
• Disable mag calibartion when there's no driver
• Fine-tune magnetic disturbance rejection in VQF
• Detecting errors when I2C writes to mag fail

[furrycoding]

Accidentally discovered that sfusion getting merged broke BMI160 axis remapping
Before - extraParam gets assigned to an int -> no downcasting
After - extraParam gets assigned to an uint8_t -> downcast to 8 bits, while 18 bits are needed for full axis remap
(without mag 9 bits are needed, however the upper bit is zero in the default remap, so it doesn't break a BMI that has no mag)
Latest commit in this PR fixes the issue