[github-actions] add building Docker images (#5273)
[github-actions] add building Docker images (#5273)

The openthread/environment and openthread/codelab_sim images are
currently built and updated via the Docker Hub service. Docker Hub
only allows a single runner at a time and is generally slower than
GitHub Actions.

This commit moves the Docker image build and update to GitHub Actions.
chshu/openthread,jwhui/openthread,chshu/openthread,lanyuwen/openthread,abtink/openthread,abtink/openthread,srickardti/openthread,lanyuwen/openthread,srickardti/openthread,openthread/openthread,jwhui/openthread,lanyuwen/openthread,bukepo/openthread,bukepo/openthread,bukepo/openthread,openthread/openthread,bukepo/openthread,lanyuwen/openthread,chshu/openthread,jwhui/openthread,chshu/openthread,abtink/openthread,lanyuwen/openthread,lanyuwen/openthread,abtink/openthread,chshu/openthread,openthread/openthread,chshu/openthread,jwhui/openthread,srickardti/openthread,srickardti/openthread,openthread/openthread