Check for either podman or docker in $PATH

[Davidnet]

Hi! I was following the tutorial in Artifact Registry, and wondering if the credential generated will be usable in podman, I was able to successfully to push images to AR without problems using podman, the only caveat was that during:

gcloud auth configure-docker us-east1-docker.pkg.dev
WARNING: `docker` not in system PATH.
`docker` and `docker-credential-gcloud` need to be in the same PATH in order to work correctly together.
gcloud's Docker credential helper can be configured but it will not work until this is corrected.

It should check if either podman or docker is installed.

Thanks for the amazing work!

[Davidnet]

I might opened this issue incorrectly, please if you pinpoint me to the correct repo to report I will be moving this issue.

Thanks

[jonjohnsonjr]

I'd probably lean toward just removing the warning altogether, but I'm not sure how to weigh the annoyance of an incorrect warning message vs the time saved from this warning message existing vs the ongoing maintenance of trying to detect any tool that reads from the docker config file.