Navigator: Support straight line mission landings (#23576)

* introduced altitude acceptance radius in position setpoint for fixed
wing guidance
- allows navigator to explicitly set the altitude acceptance radius
- needed for staright line landing support

* added ignore_alt_acceptance to position setpoint message to allow guidance
logic to ignore altitude error on waypoint
- can be useful to prevent loitering at a waypoint within a mission landing sequence

* only set altitude acceptance radius to infinity for a waypoint inside a mission landing
for fixed wing vehicles

* navigator: return altitude acceptance radius from triplet if it's valid

* FixedWingPositionControl: check if alt acceptance radius provided in position setpoint
is larger 0

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Signed-off-by: RomanBapst <bapstroman@gmail.com>
Co-authored-by: Alvaro Fernandez <alvaro@auterion.com>

msg/PositionSetpoint.msg

@@ -30,7 +30,8 @@ bool loiter_direction_counter_clockwise # loiter direction is clockwise by defau
 float32 loiter_orientation 	# Orientation of the major axis with respect to true north in rad [-pi,pi)
 uint8 	loiter_pattern		# loitern pattern to follow
 
-float32 acceptance_radius   # navigation acceptance_radius if we're doing waypoint navigation
+float32 acceptance_radius   # horizontal acceptance_radius (meters)
+float32 alt_acceptance_radius # vertical acceptance radius, only used for fixed wing guidance, NAN = let guidance choose (meters)
 
 float32 cruising_speed		# the generally desired cruising speed (not a hard constraint)
 bool gliding_enabled		# commands the vehicle to glide if the capability is available (fixed wing only)