text: Title: Streamline `lux.config` to regenerate recommendations 
  Body: Currently, `lux.config` does [not trigger a regeneration of recommendations](https://lux-api.readthedocs.io/en/latest/source/reference/config.html) and requires either explicit expiring or placing the config in the right place. We should streamline the config so that the dataframes are regenerated accordingly.
  This is non-trivial because the config is applied to all dataframes so we don't currently have a way of keeping track of all the dataframes applicable in the session. Another thing to consider is regenerating recommendations not "from scratch" but using intermediate products to update the vis, e.g., when the plot style or plotting backend is updated, only the rendering needs to happen but not the recomputation of the recommendations.