nixos/virt-manager: init

- [trunk-ng](https://github.com/ctron/trunk), A fork of `trunk`: Build, bundle & ship your Rust WASM application to the web

- [virt-manager](https://virt-manager.org/), an UI for managing virtual machines in libvirt, is now available as `programs.virt-manager`.

## Backward Incompatibilities {#sec-release-23.11-incompatibilities}

- `network-online.target` has been fixed to no longer time out for systems with `networking.useDHCP = true` and `networking.useNetworkd = true`.

{ config, lib, pkgs, ... }:

let

  cfg = config.programs.virt-manager;

in {

  options.programs.virt-manager = {

    enable = lib.mkEnableOption "virt-manager, an UI for managing virtual machines in libvirt";

    package = lib.mkPackageOption pkgs "virt-manager" {};

  };

  config = lib.mkIf cfg.enable {

    environment.systemPackages = [ cfg.package ];

    programs.dconf.enable = true;

  };

}