After #3564 and the request of #3427 (plus #3452) I decided to add a dedicated `vueConfig`object to the `nuxt.config.js` file.
The keys will be projected on Vue.config.
By default, `Vue.config.performance` is enabled in dev mode, `Vue.config.silent` is enabled in production mode.
Doc PR incoming.
Resolves: #2910, #3427