- saves a small amount of work for the ekf2 selector in multi-EKF mode (visual_odometry_aligned now ignored)
 - helps to distinguish the origin/purpose from vehicle_odometry and vehicle_visual_odometry

 - ekf2 can now run in multi-instance mode (currently up to 9 instances)
    - in multi mode all estimates are published to alternate topics (eg estimator_attitude instead of vehicle_attitude)
 - new ekf2 selector runs in multi-instance mode to monitor and compare all instances, selecting a primary (eg N x estimator_attitude => vehicle_attitude)
 - sensors module accel & gyro inconsistency checks are now relative to the mean of all instances, rather than the current primary (when active ekf2 selector is responsible for choosing primary accel & gyro)
 - existing consumers of estimator_status must check estimator_selector_status to select current primary instance status
 - ekf2 single instance mode is still fully supported and the default

Co-authored-by: Paul Riseborough <gncsolns@gmail.com>

This is important to align the flow with the IMU data and verify that
the compensation is properly done

 * HealthFlags: define bitfield using 1<<X

Co-authored-by: Matthias Grob <maetugr@gmail.com>

 * delete telemetry_heartbeat msg
 * delete unused _telemetry_status_mutex

 - new msg navigator_mission_item for inspecting navigator mission item processing

 - add min/max frequency parameters for peak detection (IMU_GYRO_FFT_MIN, IMU_GYRO_FFT_MAX)
 - remove full FFT debug logging
 - fix Quinn's second estimator
 - log sensor_gyro_fft
 - fake_gyro use PX4Gyroscope

 - this is a work in progress experiment to compute real time FFTs from raw gyro FIFO data on Cortex-m hardware (stm32f4/f7/h7, etc)

 - new sensors work item that subscribes to N x sensor_gps and publishes vehicle_gps_position
 - blending is now configurable with SENS_GPS_MASK and SENS_GPS_TAU

Co-authored-by: Jacob Crabill <jacob@volans-i.com>
Co-authored-by: Jacob Dahl <dahl.jakejacob@gmail.com>

 - only published (ORB_ID(generator_status)) and logged for now

 - inconsistency checks now run continuously instead of only preflight
 - keep inconsistencies for all sensors
 - add per sensor data validator state as overall health flag

 - purge all reminaing magnetometer IOCTL usage
 - mag calibration add off diagonal (soft iron) scale factors

 - one telemetry_status publication per mavlink instance
 - each telemetry_status has an array of HEARTBEATS

 - IMU integration move from drivers (PX4Accelerometer/PX4Gyroscope) to sensors/vehicle_imu 
 - sensors: voted_sensors_update now consumes vehicle_imu
 - delete sensor_accel_integrated, sensor_gyro_integrated
 - merge sensor_accel_status/sensor_gyro_status into vehicle_imu_status
 - sensors status output minor improvements (ordering, whitespace, show selected sensor device id and instance)

* msg: Add EKF-GSF yaw estimator logging data
* ecl: update to version with EKF-GSF yaw estimator
* ekf2: Add param control and logging for EKF-GSF yaw estimator
* logger: Add logging for EKF-GSF yaw esimtator

uORB: add bitset for faster orb_exists check and remove uORB::Subscription lazy subscribe hack/optimization

 - add PX4 bitset and atomic_bitset with testing
 - add uORB::Subscription constructor to take ORB_ID enum
 - move orb test messages into msg/

 - introduces parameter IMU_DGYRO_CUTOFF to configure the angular acceleration low pass filter
 - the angular acceleration is computed by differentiating angular velocity after the notch filter (IMU_GYRO_NF_FREQ & IMU_GYRO_NF_BW) is applied

Co-authored-by: Julien Lecoeur <jlecoeur@users.noreply.github.com>

 - split out integrated data into new standalone messages (sensor_accel_integrated and sensor_gyro_integrated)
 - publish sensor_gyro at full rate and remove sensor_gyro_control
 - limit sensor status publications to 10 Hz
 - remove unused accel/gyro raw ADC fields
 - add device IDs to sensor_bias and sensor_correction
    - vehicle_angular_velocity/vehicle_acceleration: check device ids before using bias and corrections