Create branch(es) where all based off the same base image

[MiguelRodo]

At the moment, they're all different (singularity for space, GitPod for speed and codespace for lower cost), but that's not great.

Can try the following:

• Based off Microsoft universal
  • Saves cost on Codespace
  • Slower on GitPod to create initially, but oh well.
• Based off rocker images
  • Will need to add radian
  • Costs more on codespaces, and needs some extra setup for GitPod, but it will make them all exactly the same and mean that the Ubuntu images kind of match the R versions, which has been the biggest plague. I think it's worth it for an extra R30 a month on Codespaces stoarage.