nixos/dhcpcd: use `networking.resolvconf.package`
nixos/dhcpcd: use `networking.resolvconf.package`

Allow using the appropriate resolver implementation to set DNS entries
(typically systemd-resolved instead of openresolv).

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs