RoboBoat01 reference model

[caguero]

This pull request adds 1 of 2 of the RoboBoat reference models. I decided to add it to this repository to make it easier to modify by RoboBoat users, as opposed to upstreaming it to Fuel.

• [x] Basic SDF.
• [x] Collisions based on simple-shape geometries.
• [x] Tweaked inertias
• [x] Thruster plugin
• [x] Hydrodynamics plugin
• [x] Surface plugin attached to each pontoon.

How to test it?

Add the following block to worlds/sydney_regatta.sdf.

<!-- RoboBoat 01 -->
<include>
  <name>roboboat01</name>
  <pose>-528 184 0 0 0 0</pose>
  <uri>roboboat01</uri>
</include>

Recompile VRX and launch it:

GZ_VERSION=garden colcon build --merge-install
ros2 launch vrx_gz competition.launch.py world:=sydney_regatta

Spin the thrusters:

gz topic -t /model/roboboat01/joint/right_engine_propeller_joint/cmd_thrust -m gz.msgs.Double -p 'data: 1'