[SRE-104] Add Nix Config

[rvl]

Thanks @craigem and @disassembler - for a library such as this, nix building out-of-tree is the right thing to do in my opinion.

Here is a nix expression which should work:

# From https://input-output-hk.github.io/haskell.nix/tutorials/getting-started/#scaffolding
# Build with: nix-build test.nix -A cardano-transactions.components.exes.cardano-tx
{ haskellNix ? import (builtins.fetchTarball "https://github.com/input-output-hk/haskell.nix/archive/master.tar.gz") {}
, nixpkgsSrc ? haskellNix.sources.nixpkgs-2003
, nixpkgsArgs ? haskellNix.nixpkgsArgs
, pkgs ? import nixpkgsSrc nixpkgsArgs
}: pkgs.haskell-nix.project {
  src = pkgs.fetchgit {
    url = "https://github.com/input-output-hk/cardano-transactions";
    rev = "73112de784d266ced27f36da9bc1c920f754578a";
    sha256 = "04lhjm2bg2cchp2dxs030vzd8hkmh5d0ppwilg03q7z9213q84bf";
  };
  resolverSha256 = "0adwdyg240bjfwjigpbcva137hv8lanlmw67z32znw2wd4s8x8cc";
  sha256map = {
    "https://github.com/input-output-hk/cardano-base"."5e0b8bc8c7862be12da6989440f8644ba7c1e1cf" = "06i2wpla5hp4vz873zqy1f2p0pmbhnkmabw3ibhcf476qh3vfa3p";
    "https://github.com/input-output-hk/cardano-crypto"."2547ad1e80aeabca2899951601079408becbc92c" = "1p2kg2w02q5w1cvqzhfhqmxviy4xrzada3mmb096j2n6hfr20kri";
    "https://github.com/input-output-hk/cardano-ledger-specs"."ee92681752dc1a27ac77cb3466af8dca4ade997f" = "14k6dfq8ssc3c4shll813b8wfkf9vgsz2djvg2sll9pf2fz2g1vi";
    "https://github.com/input-output-hk/cardano-node"."924a6f7d8c2bdb1bf525be8b0d5626e440697b01" = "0bi1vwmb1w6wc2szpr8v1nbsci9y36lnjr4v5pli1wvll1hhpw3c";
    "https://github.com/input-output-hk/cardano-prelude"."316c854d1d3089f480708ad5cd5ecf8a74423ddd" = "1srbl3jrkmpwypdz0yrx4nmah3qcsr93dp48zx2bamg51c4hcsyj";
    "https://github.com/input-output-hk/cardano-shell"."601bb4324c258e3c8cbd2d532e5696fd09e2582e" = "0zzd711zgj62l729hyymnv0i6jn3rx8yrww2b4a8l3csf1d9xv7n";
    "https://github.com/input-output-hk/cardano-sl-x509"."43a036c5bbe68ca2e9cbe611eab7982e2348fe49" = "1aw7ns8lv51fjf45k8yzils2j7a6bqzy8hn65kb3z0dn1qsm8x88";
    "https://github.com/input-output-hk/goblins"."26d35ad52fe9ade3391532dbfeb2f416f07650bc" = "17p5x0hj6c67jkdqx0cysqlwq2zs2l87azihn1alzajy9ak6ii0b";
    "https://github.com/input-output-hk/iohk-monitoring-framework"."efa4b5ecd7f0a13124616b12679cd42517cd905a" = "0h1h5ifl5d7dl3y6fym9pjd6rfrbh5rbyxs0xw5las503pibv2bf";
    "https://github.com/input-output-hk/ouroboros-network"."ceafa31844e6e9883d5d5634544045eab9c5f2e9" = "08zkx4si4kb761n4hcmp1dmfppfgjm56z3flsdfd7qvm9kn4l78l";
    "https://github.com/well-typed/cborg"."42a83192749774268337258f4f94c97584b80ca6" = "1smjni26p14p41d1zjpk59jn28zfnpblin5rq6ipp4cjpjiril04";
    "https://github.com/input-output-hk/snoyberg/http-client.git"."" = "1p2kg2w02q5w1cvqzhfhqmxviy4xrzada3mmb096j2n6hfr20k00";
    "https://github.com/snoyberg/http-client.git"."1a75bdfca014723dd5d40760fad854b3f0f37156" = "0537bjhk9bzhvl76haswsv7xkkyzrmv5xfph3fydcd953q08hqdb";
    "https://github.com/"."" = "1p2kg2w02q5w1cvqzhfhqmxviy4xrzada3mmb096j2n6hfr20k00";
  };
}