Barrel detection with CV

[oswinso]

One of our TODOs in line_layer: https://github.com/RoboJackets/igvc-software/blob/fbdda166b5672364f9161ee61b46e74a81d24af6/igvc_navigation/src/mapper/line_layer.cpp#L202-L232

While we will have a neural network that can detect barrels as well, as backup + baseline let's get a node that does barrel detection in OpenCV.

Probably needs a design document for the algorithm.

AC: A node that performs barrel segmentation using non-ml techniques such as opencv