Fix components in build-type: Custom packages

These components may depend on the `library` component of the package however `plan.json` does not include that dependency (since cabal will build all the components at once).  This fix adds the library component as a dependency of the other components.

Author: hamishmack

flake.nix

@@ -90,7 +90,7 @@
     let
       callFlake = import flake-compat;
 
-      ifdLevel = 3;
+      ifdLevel = 0;
       runningHydraEvalTest = false;
       compiler = "ghc928";
       config = import ./config.nix;

lib/load-cabal-plan.nix

@@ -47,7 +47,7 @@ let
               name = pkgs.lib.removePrefix "${prefix}:" n;
               value = (if cabal2nixComponents == null then {} else cabal2nixComponents.${collectionName}.${name}) // {
                 buildable = true;
-              } // lookupDependencies hsPkgs c.depends c.exe-depends;
+              } // lookupDependencies hsPkgs (c.depends ++ pkgs.lib.optional (p ? components) p.id) c.exe-depends;
             in { inherit name value; }
           )) components));
     in