add support for proxmox
Something about 1000 words:
This is one of (or the only?) places upstream that needs a patch: https://git.proxmox.com/?p=pve-container.git;a=blob;f=src/PVE/LXC/Setup.pm;hb=7e91b0f84fe2fa7a86db5780e69c5a2150453d3f#l45
However to support features like user creation, SSH key installation, permissions, and such, we need to look at whether our existing tarballs are sufficient or if we have to spin a Proxmox-specific tarball.
This issue is to track, start-to-end, all steps needed to get Adélie containers working flawlessly on Proxmox.