fix(abaca + helix): actually set the right nixd configs cause nixd is weird

modules/home/helix.nix

···
     };
     languages = {
       language-server.nixd = {
-        config = {
+        config.nixd = {
           nixpkgs = {
                 expr = "import \"\${(builtins.getFlake (builtins.toString ./.)).inputs.nixpkgs}\" { }";
           };

pkgs/ab/abaca/package.nix

···
     };
     languages = {
       language-server.nixd = {
-        config = {
+        config.nixd = {
           nixpkgs = {
                 expr = "import \"\${(builtins.getFlake (builtins.toString ./.)).inputs.nixpkgs}\" { }";
           };