Atomic HRS reads (#1845)

- Combine the reading of all `HRS3300` registers into one I2C read so data is not partial
- Downsizes both HRS and ALS to 16bit as the sensor does not generate larger than
  16bit values in its current configuration
  - Increasing the resolution by 1 bit doubles the sensor acquisition time,
    since we are already at 10Hz we are never going to use a higher resolution
  - The PPG algorithm buffers for ALS/HRS are already 16bit anyway
- Remove functions for setting gain / drive that are unused throughout the codebase
- Calculate constants with constexpr

src/heartratetask/HeartRateTask.cpp

@@ -70,7 +70,8 @@ void HeartRateTask::Work() {
     }
 
     if (measurementStarted) {
-      int8_t ambient = ppg.Preprocess(heartRateSensor.ReadHrs(), heartRateSensor.ReadAls());
+      auto sensorData = heartRateSensor.ReadHrsAls();
+      int8_t ambient = ppg.Preprocess(sensorData.hrs, sensorData.als);
       int bpm = ppg.HeartRate();
 
       // If ambient light detected or a reset requested (bpm < 0)