Update to Gazebo Harmonic/Jazzy

[ana-GT]

Feature description

The simulation package needs a few updates to work with Gazebo Harmonic in Jazzy, mainly: (1) Update on ros2 control tag, and (2) Add a hook so the robot's meshes are correctly found when launching the robots in gazebo.

Implementation considerations

Update ros2 control tags and add a hook for gazebo to find the simulation's models/meshes.

[asimonov]

Status: the environment-hook part (GZ_SIM_RESOURCE_PATH / GZ_SIM_SYSTEM_PLUGIN_PATH alongside the IGN_GAZEBO_* variables) is in #48, together with the ros2_control tags for the lunar pole rover model (xacro properties keyed on ROS_DISTRO select the Ignition or Gazebo names). Still to do for this issue: the same treatment for the canadarm and curiosity models, which carry ign_ros2_control/IgnitionSystem and libign_ros2_control-system only. The Jazzy canadarm2 and curiosity_rover demos are unaffected in the meantime since they ship their own model copies.