Add the next_hop script.

This script determines the next hop for a packet leaving this machine destined for the given address.

nix/configuration/roles/network/files/next_hop_linux.bash

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+#
+set -euo pipefail
+IFS=$'\n\t'
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+exec ip route get "${@}"