commander: Add prearm check for flight termination

[julianoes]

This adds a pre-arm check that prevents arming after a flight termination. This probably requires some discussion as it is related to the ongoing discussion in #19198.

[dagar]

This solution seems fine, although another idea is that this could probably be done directly in arming_state_transition() with the actuator_armed flags in place and entirely avoid having to update vehicle_status_flags.

PX4-Autopilot/src/modules/commander/state_machine_helper.cpp

Lines 252 to 281 in d3b3de7

	armed.lockdown = true;
	status_flags.system_sensors_initialized = true;
	/* recover from a prearm fail */
	if (status.arming_state == vehicle_status_s::ARMING_STATE_STANDBY_ERROR) {
	status.arming_state = vehicle_status_s::ARMING_STATE_STANDBY;
	}
	// HIL can always go to standby
	if (new_arming_state == vehicle_status_s::ARMING_STATE_STANDBY) {
	valid_transition = true;
	}
	}
	if (!hil_enabled &&
	(new_arming_state == vehicle_status_s::ARMING_STATE_STANDBY) &&
	(status.arming_state != vehicle_status_s::ARMING_STATE_STANDBY_ERROR)) {
	// Sensors need to be initialized for STANDBY state, except for HIL
	if (!status_flags.system_sensors_initialized) {
	feedback_provided = true;
	valid_transition = false;
	}
	}
	// Finish up the state transition
	if (valid_transition) {
	bool was_armed = armed.armed;
	armed.armed = (new_arming_state == vehicle_status_s::ARMING_STATE_ARMED);
	armed.ready_to_arm = (new_arming_state == vehicle_status_s::ARMING_STATE_ARMED)