Make Webots compliant with ROS4HRI

[severin-lemaignan]

Webots has nice support for human simulation; it would be great if it exposes ROS4HRI-compliant topics for these.

ROS4HRI (REP-155: https://www.ros.org/reps/rep-0155.html) defines a set of topics and messages to expose visible humans to a ROS system. It supports both ROS1 and ROS2.

For instance, the 2D skeleton of the human is exposed under a /humans/bodies/<arbitrary body id>/skeleton2d. The 3D skeleton is exposed as a joint state. Faces are exposed as region of interest and/or facial landmarks. etc.

To start with, some of this information might be easier for webots to generate (eg, ROI of faces and bodies), and full support can be added little by little.

This would make webots the first ROS simulator to be ROS4HRI/REP-155 compliant.

As one of the original authors of REP-155, I would be happy to provide some support if some parts of the spec are not clear.