enable intra-process communication for point clouds

[christian-rauch]

The node currently publishes point cloud messages directly and does not use a unique shared pointer, which prevents using efficient zero-copy intra-process communication as it requires copying the data between nodes in the same process.

This PR fixes this by publishing the point cloud via a unique shared pointer. I verified by the address of the data vector that the camera node and a point cloud subscriber indeed share that message without copying data.

The PR also contains some cleanup commits and one commit to guard different method signatures behind a version check to enable compilation on Ubuntu 20.04 with ROS2 rolling. Note that those checks should be done by library version and not ROS2 distribution names, as the same ROS2 distribution (e.g. rolling in this case) can have different versions of a library on different Ubuntu versions.

[christian-rauch]

@Nir-Az The CI is failing for galactic for the same reasons as in #2381 (comment) (Could not resolve the rosdep key 'ros_workspace'). Are there plans to fix the CI for galactic or can we merge this PR with those pipelines failing?

[Nir-Az]

@Nir-Az The CI is failing for galactic for the same reasons as in #2381 (comment) (Could not resolve the rosdep key 'ros_workspace'). Are there plans to fix the CI for galactic or can we merge this PR with those pipelines failing?

Thanks for the PR, looks like a great enhancement.
I agree about the versions vs distro check, thanks for that too.
We will review the PR and test it.
The galactic fail of pre-release can be ignored, looks like a regression from industrial-ci
The other failure seems like a network glitch in GHA, I reran it now lets see.. should be OK.

[christian-rauch]

@Nir-Az Can you approve the CI pipeline for this PR?

[Nir-Az]

Great enhancement, thanks!

[tonynajjar]

With this PR should the readme be updated? It still says that pointclouds are not supported for ipc

[Nir-Az]

With this PR should the readme be updated? It still says that pointclouds are not supported for ipc

You are right, thanks.
If you can PR it, it would be even awesome :)