neovim: set meta in the unwrapped version

instead of the wrapper: the wrapper will inherit the value from the unwrapped version. This allows nix run nixpkgs#neovim-unwrapped to work too.

pkgs/applications/editors/neovim/default.nix

@@ -131,6 +131,7 @@ in
         - Improve extensibility with a new plugin architecture
       '';
       homepage    = "https://www.neovim.io";
+      mainProgram = "nvim";
       # "Contributions committed before b17d96 by authors who did not sign the
       # Contributor License Agreement (CLA) remain under the Vim license.
       # Contributions committed after b17d96 are licensed under Apache 2.0 unless

pkgs/applications/editors/neovim/wrapper.nix

@@ -131,7 +131,6 @@ let
       hydraPlatforms = [];
       # prefer wrapper over the package
       priority = (neovim.meta.priority or 0) - 1;
-      mainProgram = "nvim";
     };
   };
 in