docker: update Dockerfiles to use focal images

[russkel]

To close #382

• use focal base images instead of bionic, including using newer version of libglvnd
• runtime=nvidia is deprecated, gpus=all has replaced it in newer
  versions of docker

This has not been built or tested by me.

[j-rivero]

I tried the changes using the new Dome release. Everything seems fine except that the ignition-dome package is not yet released, should be ready tomorrow. Let's wait 48 hours to give this a final run. Thanks @russkel for the changes!

[j-rivero]

If I understand it correctly, this change is not strictly related to the update to focal but more about the version of docker in the user system. I think we can update it as you did in the PR since modern docker uses the native nvidia integration.

[russkel]

This is correct. I decided to update to reflect the docs found at https://docs.nvidia.com/datacenter/cloud-native/container-toolkit/install-guide.html#docker to hopefully reduce confusion.

I'm not too familiar with what is actually going on in docker/nvidia-runtime internals so maybe this change in CLI arguments is required.

[j-rivero]

Everything seems fine except that the ignition-dome package is not yet released, should be ready tomorrow

@russkel now that dome in released, we are fine to merge these changes. I would need a couple of things from you: could you please rebase/merge the changes on ign-gazebo4 with your branch? While doing that we need to address the DCO bot failure in the CI, there are instrcutions in the "Details" link https://github.com/ignitionrobotics/ign-gazebo/pull/388/checks?check_run_id=1181732463?

[russkel]

Hi @j-rivero, done as you have asked.

[j-rivero]

thanks you very much! ready to go.