Add the ability for `withPackages` and `withExtensions` to be written in `devbox.json`

[kpervin]

What problem are you trying to solve?

There are certain nixpkgs that require configuration using withExtensions and withPackages. Currently, the only way to utilize those packages in that way using DevBox is to create a flake, which feels antithetical to DevBox's proposition of abstracting Nix.

Example, for using the azure-cli with azure-cli-extensions:

{
  description = "A flake to install azure-cli";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, flake-utils, }:
    flake-utils.lib.eachDefaultSystem (system:
      let pkgs = nixpkgs.legacyPackages.${system};
      in {
        formatter = pkgs.nixfmt;
        packages = {
          default = pkgs.azure-cli.withExtensions
            [ pkgs.azure-cli-extensions.terraform ];
        };
      });
}

{
  "$schema": "https://raw.githubusercontent.com/jetify-com/devbox/0.13.6/.schema/devbox.schema.json",
  "packages": {
    "path:./.flakes/azure-cli": "",
  }
}

What solution would you like?

Allow for withExtensions and withPackages, possibly also override, to be definable in devbox.json:

{
  "$schema": "https://raw.githubusercontent.com/jetify-com/devbox/0.13.6/.schema/devbox.schema.json",
  "packages": {
    "azure-cli": {
      "version": "latest",
      "withExtensions": {
        "azure-cli-extensions.terraform": "latest"
      }
    }
  }
}

Additionally, also including cli functionality to be able to add these to devbox.json, ex: devbox add azure-cli --with-extensions azure-cli-extensions.terraform .

Alternatives you've considered

No response

[idabmat]

Possible duplicate of #1829 ?

[kpervin]

Possible duplicate of #1829 ?

I think this exposes a similar issue, but this is a feature request regarding implementation so I believe they are distinct enough.