This gets nix from the `latest` [symlink](https://nixos.org/releases/nix/latest/) by default, so this file doesn't need to be kept in sync with nix releases.
* nix: multi-user install on Linux
* Invoke nix-install with --daemon option
Co-authored-by: Travis A. Everett <travis.a.everett@gmail.com>
* nix: default to 2.3.6
* nix: fix install url
* write config to /tmp/nix.conf
The linux build is objecting because /etc/nix/ already exists.
* stop creating /nix for 2.2.x installers
Prior to https://github.com/NixOS/nix/pull/3054, the daemon installer
required /nix to be empty. This no longer creates them.
I *think* they are vestigial now that this uses a daemon install. But,
I can't swear I *know* they're obsolete. :)
Co-authored-by: Travis A. Everett <travis.a.everett@gmail.com>