Add AMS (Auto Maneuver System, aka emergency descend) mode support

[bresch]

This PR allows the SDK to trigger AMS on the flight controller introduced here:
PX4/PX4-Autopilot#11169

Example of how to use the code:

// AMS
std::cout << "Engaging AMS..." << std::endl;
const Action::Result ams_result = action->auto_maneuver_system();
if (takeoff_result != Action::Result::SUCCESS) {
std::cout << ERROR_CONSOLE_TEXT << "AMS failed:" << Action::result_str(ams_result)
<< NORMAL_CONSOLE_TEXT << std::endl;
return 1;
}

[JonasVautherin]

Looks good, but you need to fix style. You can run the following command for that:

$ make fix_style

[julianoes]

Thanks for the pull request.

Is this AMS thing in PX4? Because I'm looking at https://github.com/PX4/Firmware/blob/master/src/modules/commander/px4_custom_mode.h and I don't see it there.

[julianoes]

@bresch please follow up.

[julianoes]

@bresch bump 😄

[JonasVautherin]

I updated the branch and fixed style, but the CI is still failing because the documentation is lacking fields.

[julianoes]

Thanks but also this is not in upstream yet anyway, so I'm confused how it even works.

[bresch]

Sorry I'm not really responsive here... It's not merged yet in the firmware because of some changes in the mission_item. I'll come to you @julianoes to discuss about that.

[julianoes]

Ok, this needs to wait for the PX4 change to be merged first then.

[julianoes]

Please re-open when it is merged in PX4 and we should consider it again.