Feature request

Feature description

Great work on the collision monitor, I've been looking into the implementation and was wondering whether we could detach/modularize it into two parts to use them separately.

The Sensing: detection of an obstacle inside a polygon using different sources. I could imagine this part being a standalone package to be useful for other applications, e.g. activating LEDs if an object comes within range
Basically a node that subscribes to the sources and output a custom msg that contains the information for which polygons are triggered.

The Action: subscribing to part 1 and limiting the velocity accordingly

Do you see part 1 as generally useful? We could ask that question on ROS Discourse.