Interest in PR(s) for extracting Container behaviour into a trait?

Thanks for open-sourcing this super useful project. I've recently been using a fork of rustwide at work which I use for building several of our in-house crates.

Currently, rustwide is coupled to docker, and a downstream change I have found useful is extracting the Container logic into a separate trait so that users can 'bring-your-own-container' (VM / LXC / bare-metal etc). This flexibility has made integrating rustwide with our existing infrastructure much easier.

Would this work be of benefit to the greater community? I'd be happy to raise a PR for this if so, or even make this change somewhere else if rustwide folks are keen - you will have better understanding than me of where the right abstraction boundary lies! I don't expect rustwide to support non-docker containers, but this change may allow others to do so without having to fork?

Start by reading the Container logic linked in src/cmd/sandbox.rs and review how rustwide is currently coupled to Docker. Compare that boundary with the proposed trait approach and determine what abstraction would let users provide VM, LXC, or bare-metal behavior without requiring rustwide to support those containers directly. Done means the design is agreed and the default Docker behavior remains usable.