Moved scripts to the overlay folder to be used as packages

All scripts have been moved to the overlay folder in the top level directory

Overlay is now instantiated per configuration to make use of the host variable

overlay/scripts/commands/icanhazip.nix

@@ -0,0 +1,18 @@
+{ pkgs }:
+
+pkgs.writeShellApplication {
+  name = "icanhazip";
+  runtimeInputs = with pkgs; [ iproute2 curl gawk coreutils ];
+  text = ''
+    if [ $# -eq 0 ]; then
+      echo "Public IP: $(curl -s icanhazip.com -4)"
+      ip route | awk '/default/ {print "Default Gateway: " $3} /src/ {print "Local IP: " $9}' | head -n 2
+    else case $1 in
+      "-p" ) echo "Public IP: $(curl -s icanhazip.com -4)";;
+      "-d" ) ip route | awk '/default/ {print $3}';;
+      "-l" ) ip route | awk '/src/ {print $9}';;
+      * ) echo "Options: -p, -d or -l for public ip, default gateway, and local ip respectively"; echo "i.e. icanhazip -p"
+      esac
+    fi
+  '';
+}