Add a ready field in the sensor struct

[wispl]

Currently, in our downstream code we do

enum sensors {
  BMP581,
  BMI088,
  NUMBER_SENSORS
};
struct sensor sensors[NUMBER_SENSORS];
bool sensors_res[NUMBER_SENSORS];

It is kind of clunky to have a separate array just to store the ready status of the sensors. We should move this into the actual sensor struct and optionally add a method to check if the sensor is ready. After this is done, make sure to update the downstream code to take advantage of this change.