feat(fun/amsterdump): Add distance matrix lookup for fundu results

This contains a little tool that can make requests to the Google Maps
API for distance matrix lookups from Fundu results to Schiphol Airport
and Amsterdam Centraal.

<3 edef!

fun/amsterdump/default.nix

@@ -0,0 +1,13 @@
+{ pkgs, ... }:
+
+pkgs.buildGo.program {
+  name = "amsterdump";
+  srcs = [
+    ./main.go
+  ];
+
+  deps = with pkgs.third_party; map (p: p.gopkg) [
+    # gopkgs."golang.org".x.oauth2.google
+    gopkgs."googlemaps.github.io".maps
+  ];
+}