Add shake-bench component to nix build

Author: jneira

nix/default.nix

@@ -17,6 +17,7 @@ let
           haskellPackages.extend (pkgs.haskell.lib.packageSourceOverrides {
             haskell-language-server = gitignoreSource ../.;
             ghcide = gitignoreSource ../ghcide;
+            shake-bench = gitignoreSource ../ghcide/shake-bench;
             hie-compat = gitignoreSource ../ghcide/hie-compat;
             hls-plugin-api = gitignoreSource ../hls-plugin-api;
             hls-tactics-plugin = gitignoreSource ../plugins/tactics;

shell.nix

@@ -26,6 +26,7 @@ let defaultCompiler = "ghc" + lib.replaceStrings ["."] [""] haskellPackages.ghc.
 
     packages = p: [ p.haskell-language-server
                     p.ghcide
+                    p.shake-bench
                     p.hie-compat
                     p.hls-plugin-api
                     p.hls-tactics-plugin