Publish docker image to GHCR and DockerHub

[MattF-NSIDC]

Description

Build and publish docker images with GH Actions to GHCR and DockerHub

This entails some other changes; for example, we were always mounting code into containers with volumes. Now, we should have the correct version of the code baked in to the container.

Checklist

If an item on this list is done or not needed, simply check it with [x].

• [x] Config lockfile updated (inv config.export > qgreenland/config/cfg-lock.json)
• [x] Version bumped if needed (bumpversion (major|minor|patch|prerelease|build)
• [x] CHANGELOG.md updated
• [x] Documentation updated if needed
• [x] New unit tests if needed

Fixes #542 , fixes #564

[MattF-NSIDC]

Published the first latest image:

https://github.com/nsidc/qgreenland/pkgs/container/qgreenland https://hub.docker.com/repository/docker/nsidc/qgreenland

After publishing with this PR, I changed the workflow triggers so future PRs won't trigger publishes.