feat(neovim): add lsp, autoformat and completions

programs/neovim/default.nix

@@ -6,14 +6,19 @@
     extraLuaConfig = builtins.readFile ./init.lua;
 
     extraPackages = with pkgs; [
-      (lua5_1.withPackages (ps: with ps; [ luarocks ]))
+      lua5_1
+      nixfmt-rfc-style
       tree-sitter
     ];
 
     plugins = with pkgs.vimPlugins; [
       barbar-nvim
       catppuccin-nvim
+      cmp-nvim-lsp
+      lsp-format-nvim
       lualine-nvim
+      nvim-cmp
+      nvim-lspconfig
       nvim-treesitter.withAllGrammars
       nvim-web-devicons # for lualine
     ];