Configure the exposure mode on the camera
#include <camera/camera_3a.h>
camera_error_t camera_set_exposure_mode(camera_handle_t handle, camera_exposuremode_t mode)
Use this function to set the active exposure mode on the camera. To determine valid exposure modes that can be set, call the camera_get_exposure_modes() function.
The viewfinder must be running before calling this function.
CAMERA_EOK when the function successfully completes, otherwise another camera_error_t value that provides the reason that the call failed.