Improve nix flake

[lluchs]

This fixes the nix flake (it didn't work with current nixpkgs since the old libdwarf was removed and some Python trouble) and implements some improvements:

• The plugin configuration can be overwritten by flake consumers and the flake can reduce the dependencies accordingly.
• PyPANDA is built separately (mostly to avoid rebuilding all of PANDA with every change while figuring out Python packaging)
• I also updated Wireshark to the newest version supported by the network plugin

cc @be32826 who built the flake originally

[be32826]

This will only work when running nix build in the cloned repo, but it won't work when used as a dependency. I get this error with nix build github:lluchs/panda/flake:

error: cannot fetch input 'path:./panda/plugins/config.panda' because it uses a relative path

Maybe plugin customization can be done at a different level from the flake inputs, such as with .override?

[lluchs]

Ah, annoying. Thanks for catching that. .override unfortunately doesn't easily work without making the whole thing a nixpkgs overlay.

I've seen people suggest an input "path:/dev/null" for optional external configuration. I will try that.

[be32826]

.override unfortunately doesn't easily work without making the whole thing a nixpkgs overlay.

I think you might be able to just change the panda package definition from

panda = pkgs.stdenv.mkDerivation {
  ...
}

to something like

panda = pkgs.callPackage
  ({ plugins ? builtins.readFile ./panda/plugins/config.panda }:
    pkgs.stdenv.mkDerivation {
      ...
    }) {}

[lluchs]

I implemented file:/dev/null as input now since it was simpler from what I already had. nix build github:lluchs/panda/flake works now, as well as local builds from the repository and overriding the configuration from another flake.