[npm] install deps "global-sytle" (elastic#9136)

Installing dependencies "global-style" creates a top-level directory in `node_modules` for each direct dependency, and then creates a flat tree of dependencies inside each of those.

I prefer this method because it prevents accidentally depending on a dependency of a dependency, and makes it easier to find dependencies in `node_modules`.

Unfortunately the `node_modules` directory will be a little deeper.

.npmrc

@@ -1 +1,2 @@
 save-exact=true
+global-style=true