Range check cleanup (#782)

* EKF: centralize range finder tilt check

* Ekf-control: do not double check for terrain estimate validity

isRangeAidSuitable can only return true if the terrain estimate is valid
so there is no need for an additional check

* range_finder_checks: restructure the checks to avoid early returns

There is now only one clear path that can lead to the validity being
true.
Furthermore, if the _rng_hgt_valid is true, we can trust it and we don't
need for additional checks such as tilt.

The case where we need to provide fake measurements because the drone is
on the ground and the range finder data is bad is already handled
in "controlHeightFusion" so there is no need to hack the range finder
checks with that.

* Add Sensor and SensorRangeFinder classes

The purpose is to encapsulate the checks for each sensor in a dedicated
class with the same interface

* SensorRangeFinder: encapsulate in estimator::sensor namespace

* EKF: rename _sensor_rng to _range_sensor

* Range checks: include limits in valid range

* RangeChecks: update comment in the continuity checks

* RangeChecks: move more low-level checks in functions

Also move setTilt out of the terrain estimator, this is anyway protected internally
to not compute cos/sin if the parameter did not change.

* Sensor: remove unused virtual functions

Those are not required yet but can still be added later

* SensorRangeFinder: re-organise member variables

Also rename getRangeToEarth to getCosTilt

* SensorRangeFinder: split setSensorTilt and setCosMaxTilt functions

* SensorRangeFinder: Add a few unit tests

- good data
- tilt exceeded
- max range exceeded

* SensorRangeFinder: set hysteresis in us instead of ms

* SensorRangeFinder: Add more tests

* SensorRangeFinder: update continuity, hysteresis and stuck tests

* SensorRangeFinder: rename variables

* SensorRangeFinder: get rid of "delayed" specification

From the SensorRangeFinder class point of view, it's not relevant to
know if the data is delayed or not

* SensorRangeFinder: move time_last_valid out of stuck check

* SensorRangeFinder: rename file names to sensor_range_finder

* SensorRangeFinder: address Kamil's comments

* SensorRangeFinder: Add more tilt tests

* SensorRangeFinder: store current tilt offset

This is to avoid recomputing cos/sin functions at each loop

EKF/estimator_interface.h

@@ -47,6 +47,7 @@
 #include "AlphaFilter.hpp"
 #include "imu_down_sampler.hpp"
 #include "EKFGSF_yaw.h"
+#include "sensor_range_finder.hpp"
 
 #include <geo/geo.h>
 #include <matrix/math.hpp>
@@ -230,8 +231,7 @@ public:
 	// set sensor limitations reported by the rangefinder
 	void set_rangefinder_limits(float min_distance, float max_distance)
 	{
-		_rng_valid_min_val = min_distance;
-		_rng_valid_max_val = max_distance;
+		_range_sensor.setLimits(min_distance, max_distance);
 	}
 
 	// set sensor limitations reported by the optical flow sensor
@@ -436,7 +436,7 @@ protected:
 	magSample _mag_sample_delayed{};
 	baroSample _baro_sample_delayed{};
 	gpsSample _gps_sample_delayed{};
-	rangeSample _range_sample_delayed{};
+	sensor::SensorRangeFinder _range_sensor{};
 	airspeedSample _airspeed_sample_delayed{};
 	flowSample _flow_sample_delayed{};
 	extVisionSample _ev_sample_delayed{};
@@ -450,8 +450,6 @@ protected:
 	float _air_density{CONSTANTS_AIR_DENSITY_SEA_LEVEL_15C};		// air density (kg/m**3)
 
 	// Sensor limitations
-	float _rng_valid_min_val{0.0f};	///< minimum distance that the rangefinder can measure (m)
-	float _rng_valid_max_val{0.0f};	///< maximum distance that the rangefinder can measure (m)
 	float _flow_max_rate{0.0f}; ///< maximum angular flow rate that the optical flow sensor can measure (rad/s)
 	float _flow_min_distance{0.0f};	///< minimum distance that the optical flow sensor can operate at (m)
 	float _flow_max_distance{0.0f};	///< maximum distance that the optical flow sensor can operate at (m)