Support nix package install method

I'd like the 3.x versions of edgedb-cli to be easier to add to Nixpkgs. There is a [2.3.1 version available](https://github.com/NixOS/nixpkgs/blob/nixos-23.05/pkgs/tools/networking/edgedb/default.nix), but the recent 3.x versions are using git submodule for the shared test cases and this is causing nix-build to fail, at least in the cursory attempt I made at porting over the package from 2.3 to 3.3.

I appreciate how much work went into the install script, I just prefer to manager my install in a more declarative way and nix is the best option I've seen. I'll gladly contribute work to getting the nix packages install kept current if that helps, but I'd like to know if there is support for this on the dev side?