What work needs to be done to allow sccache-dist server to run without root?

[pierzchalski]

I've wanted to set up sccache a couple of times, but each time the root/sudo requirement for the build server ends up being a blocker. I can't use docker or podman either, unfortunately.

I admit this is a pretty niche situation, but if there's an easy solution to needing root I'd love to hear it! I believe the root requirement is due to using bubblewrap, and I assume we can't get around that.

[drahnr]

#1628 is an initial implementation to use userns. I'd be happy to collect feedback. Note though, the userns part is very experimental still and has a few known issues (see comments in the PR changeset).