Add `rig docker ...`

[gaborcsardi]

rig docker run clang18
rig docker run multi
rig docker run fedora-release
rig docker run r-minimal:4.3.3
rig docker run evercran:1.0.0
rig docker list

To get a list of tags for an image, use https://github.com/orgs/community/discussions/26279 for GHCR, and use https://stackoverflow.com/a/68654659/604364 for Docker Hub

Could support

• https://github.com/r-hub/containers
• https://github.com/r-hub/r-minimal
• https://github.com/r-hub/evercran
• https://github.com/r-lib/rig
• https://github.com/rstudio/r-docker (?)
• Rocker images?