nix2container integration

[tennox]

I've come to love nix2container, and wondered whether that's (still) a plan to integrate into arion - and if so, how much effort do you think it might be?
I might even give it a shot 🤔

[roberth]

I don't know how familiar you are with it.
An integration would need to

• add the new image "format" somewhere near here
• invoke nix2container here
• add a test case

It seems like a manageable surface area to me.