Add ‘packages’ to the federated example cache group.

Since the dependencies are in ‘packages/‘, this combines them, reducing the number of scripts at page load from around 100 script files to around 40.

examples/federated/core_package/webpack.config.js

@@ -196,7 +196,7 @@ module.exports = [
         chunks: 'all',
         cacheGroups: {
           jlab_core: {
-            test: /[\\/]node_modules[\\/]@(jupyterlab|lumino)[\\/]/,
+            test: /[\\/](node_modules[\\/]@(jupyterlab|lumino)|packages)[\\/]/,
             name: 'jlab_core'
           }
         }