mullvad: init at 2022.1

[cole-h]

This package includes the CLI binaries for mullvad, but does not attempt
to build the GUI. This allows it to be (more) cross-platform than the
mullvad-vpn package, which depends on a tool that is unavailable for
e.g. ARM platforms.

Motivation for this change

I tried to set up Mullvad on an aarch64 machine, but was relegated to a wg-quick config file generated on their website. Their reasoning for not providing an ARM build is that a dependency for the GUI part of their software does not support ARM (see mullvad/mullvadvpn-app#952 for more information). I'd much rather use their CLI tools than have to keep copies of the config files lying around.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 22.05 Release Notes (or backporting 21.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

---

This is still WIP because I haven't tested if it actually works (everything is properly executable, but I haven't deployed it to my aarch64 machine yet). I'm also not entirely happy with the separation between the libwg and mullvad packages, but I wasn't going to put the libwg derivation inside the mullvad package -- that would be much worse, IMO.

[cole-h]

Unable to dig into the eval error right now (likely because of the scope, I'd be willing to bet). lol it was because of the dbus_daemon alias + using cargoLock.lockFile.

However, here's proof of it running on my aarch64 machine:

[cole-h]

cc @ymarkus @Br1ght0ne @flexagoon -- Figured y'all might be interested in this, as maintainers of mullvad-vpn (the GUI app).

[cole-h]

OK, thanks to @SuperSandro2000, OpenVPN tunnels are now supported (and I've confirmed they work locally)!