Validate distortion coefficients

OpenCV calibration can return invalid distortion coefficients (resulting in non-monotonic distortion function).

Documented in camera model section: https://docs.opencv.org/master/d9/d0c/group__calib3d.html#details

Calibration should be considered failed if such values are returned and those values should not be used to perform distortion correction.

Calibration app should also report if this happens.