Caching using Docker

[agarbuno]

I wanted to test some caching using Docker and GitHub Actions. This post goes through several strategies. As a complement, this post sets the cache using the cache action. The strategies that were tested were:

1. No caching, just pulling an image with all R dependencies.
2. Using an earlier cache action, ScribeMD/docker-cache@0.2.1.
3. Using the cache action and the docker save and docker load commands.
4. Using the Docker builder (buildx) so that Docker layering is used and the docker load command.