Reflect filter bar selections in dashboard panels

In #517033 (closed), we added a configurable filter bar to the shared dashboarding framework. However, other than changes in the visualizations themselves, there's currently no way of distinguishing between panels that have been affected by the filter bar's selections or not.

Questions

• Do we need to reflect filter bar selections at the panel level?
• Do we need to indicate if a panel has not been affected by applied filters?
• Should we instead leave it up to visualizations to reflect filter bar selections as they see fit?