Update onCreateCommand to install Copilot CLI

Author: hubwriter

.devcontainer/devcontainer.json

@@ -59,9 +59,11 @@
   },
 
   // Lifecycle commands
-  "onCreateCommand": "npm ci",
+  // Install dependencies then install Copilot CLI
+  "onCreateCommand": "npm ci && npm config set \"//npm.pkg.github.com/:_authToken=$GITHUB_TOKEN\" && npm config set \"@github:registry=https://npm.pkg.github.com/\" && npm install -g @github/copilot",
+  // Start a web server and keep it running
   "postStartCommand": "nohup bash -c 'npm start &'",
-  // Set the port to be public
+  // Set port 4000 to be public
   "postAttachCommand": "gh cs ports visibility 4000:public -c \"$CODESPACE_NAME\"",
 
   // Comment out connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.