feat: separate copilot module and configuration

modules/assistant/copilot/config.nix

@@ -0,0 +1,24 @@
+{
+  pkgs,
+  config,
+  lib,
+  ...
+}:
+with lib;
+with builtins; let
+  cfg = config.vim.assistant.copilot;
+in {
+  config = mkIf cfg.enable {
+    vim.startPlugins = [
+      "copilot-lua"
+      pkgs.nodejs-slim-16_x
+    ];
+
+    vim.luaConfigRC.copilot = nvim.dag.entryAnywhere ''
+      require("copilot").setup({
+        -- available options: https://github.com/zbirenbaum/copilot.lua
+        copilot_node_command = "${cfg.copilot_node_command}",
+      })
+    '';
+  };
+}