refactor(users/grfn): build all haskell packages without ifd

Since we need to override random to 1.2.0 globally for xanthous
(otherwise propagation causes two versions of random to be propagated
for xanthous) evaluating haskell related stuff using import from
derivation can be very expensive since utilities like hpack and
cabal2nix need to be built for that. This means that for every channel
bump we potentially need to do a world rebuild of haskellPackages first.

To solve this we check in the cabal2nix-generated nix expressions for
owothia and xanthous.

Change-Id: I8fff70b4b6c303d1920f8bcac53520a09999b206
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2921
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
Reviewed-by: tazjin <mail@tazj.in>

users/grfn/owothia/default.nix

@@ -2,5 +2,11 @@
 , pkgs ? depot.third_party.nixpkgs
 , ... }:
 
-pkgs.haskellPackages.callCabal2nix "owothia"
-  (depot.third_party.gitignoreSource ./.) { }
+let
+  basePkg = pkgs.haskellPackages.callPackage ./pkg.nix { };
+in
+
+pkgs.haskell.lib.overrideSrc basePkg {
+  src = depot.third_party.gitignoreSource ./.;
+  version = "canon";
+}

users/grfn/owothia/pkg.nix

@@ -0,0 +1,16 @@
+{ mkDerivation, base, bytestring, chatter, containers, envy
+, irc-client, lens, lib, random, relude, text
+}:
+mkDerivation {
+  pname = "owothia";
+  version = "0.0.1.0";
+  src = ./.;
+  isLibrary = false;
+  isExecutable = true;
+  executableHaskellDepends = [
+    base bytestring chatter containers envy irc-client lens random
+    relude text
+  ];
+  license = "unknown";
+  hydraPlatforms = lib.platforms.none;
+}