Launch file for combined gzserver + bridge

[caguero]

🎉 New feature

Summary

This patch lets you combine the functionality from #530 and #532 into a single launch file.

How to test it?

Use the provided ros_gz_sim.launch.py (modify config_file accordingly) to run the bridge as an executable

ros2 launch ros_gz_sim ros_gz_sim.launch.py world_sdf_file:=empty.sdf config_file:=/home/caguero/ros_gz_ws/src/ros_gz/ros_gz_bridge/test/config/full.yaml

You should see messages of gzserver loading. Additionally, verify that you see the /ros_chatter topic:

caguero@cold:~/ros_gz_ws$ ros2 topic list
/parameter_events
/ros_chatter
/rosout

Confirm that no container has been created:

caguero@cold:~/ros_gz_ws$ ros2 component list

Now CTRL-C to stop all nodes and try the composable version:

ros2 launch ros_gz_sim ros_gz_sim.launch.py world_sdf_file:=empty.sdf use_composition:=True config_file:=/home/caguero/ros_gz_ws/src/ros_gz/ros_gz_bridge/test/config/full.yaml

gzserver should be running. Verify that you also see the /ros_chatter topic:

caguero@cold:~/ros_gz_ws$ ros2 topic list
/parameter_events
/ros_chatter
/rosout

And confirm that a container has been created with both nodes:

caguero@cold:~/ros_gz_ws$ ros2 component list
/ros_gz_container
  1  /ros_gz_bridge
  2  /gzserver

Test it

Checklist

• [x] Signed all commits for DCO
• [ ] Added tests
• [ ] Added example and/or tutorial
• [ ] Updated documentation (as needed)
• [ ] Updated migration guide (as needed)
• [ ] Consider updating Python bindings (if the library has them)
• [ ] codecheck passed (See contributing)
• [ ] All tests passed (See test coverage)
• [ ] While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.