Figure out how to pre-install pre-commit hooks

[jopetty]

Currently, in order to actually use the pre-commit hooks we have to remember to install them every time the docker image is recreated. It would be better if this could be done as a step in the Dockerfile and just cache it.

I think the big difficulty, however, is that we don't actually have the .git info for the repo when the Docker image is built, since we're MOUNTing it in via the devcontainer.json, so any attempt to install the hooks early (as in here) will fail when the new .git folder is copied over.