feat(users/Profpatsch/whatcd-resolver): add a simple torrent parser

The `bencode` library is anything but production-grade, but it’s
enough to parse the torrent files generated by Gazelle lol.

This should help with … I haven’t really figured out yet what it helps
with I guess. But it was fun. I like the `Parse` abstraction very
much. It can parse XML and it can parse Bencode. Good.

Change-Id: If1331de423eab3e91ce9db6e2a7eb84da51b18a2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/13211
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>

users/Profpatsch/whatcd-resolver/default.nix

@@ -12,6 +12,7 @@ let
       ./Main.hs
       ./src/WhatcdResolver.hs
       ./src/AppT.hs
+      ./src/Bencode.hs
       ./src/JsonLd.hs
       ./src/Optional.hs
       ./src/Html.hs
@@ -29,6 +30,7 @@ let
       pkgs.haskellPackages.pa-field-parser
       pkgs.haskellPackages.pa-run-command
       pkgs.haskellPackages.aeson-better-errors
+      pkgs.haskellPackages.bencode
       pkgs.haskellPackages.blaze-html
       pkgs.haskellPackages.hs-opentelemetry-sdk
       pkgs.haskellPackages.http-conduit