the Flighttask fail. A failure of the Flighttask can occur if the demanded Flighttask does
not have the required data.

will land with 0.3 of hover thurst if position nor velocity is valid

To my knowledge this hil transition function is not used anymore,
however, it makes sending the DO_SET_MODE command unnecessarily complex.
In my opinion the DO_SET_MODE command should only change the mode but
not other things like arming (already removed) and HITL state (this
commit).

Often times, I was seeing the error message "Set SYS_HITL to 1 and
reboot to enable HITL." when using QGC with a vehicle in HITL.

HITL is set via parameter which then has an impact in the startup script
where the CLI argument `-hil` is added to some of the commands that
require it (like commander as well).

This flag does not seem to be used anywhere.

after review comment request from @dagar. Thanks!

such that fractions of a second are configurable

 - #10359

added a check to ensure the initialize settings function succeeds. If it does not, the driver fails gracefully. This handles the case that the device is not there.

 * tested on SPI (px4fmu-v4pro)
 * WIP I2C support

Failure Detector - use bitmask field instead of boolean in vehicle_status msg (failure_detector_status) and instead of struct in class

Failure Detector - move "force_failsafe" flag inside circuit_breaker protection; remove PX4_WARN and send mavlink msg only once

- use pragma once guard in FailureDetector.hpp
- send Commander parent to ModuleParams and remove update_params() method
- simplify attitude checks
- FailureDetector::get_status() (previously named "get") is now a constant method that returns a constant reference

NullMixer - Send NAN instead of 0. NAN is mapped to disarmed in fmu and io. A Null mixer can now be used to set a fixed value: "disarmed" if the system is operational or "failsafe" in failsafe mode

FailureDetector - Add check for non-zero roll/pitch failure parameters. Rename 'result' into 'updated'

FailureDetector - New class, first working simple implementation. Outputs PX4_ERR messages if roll or pitch is exceeded.