FIX: Support filtering against multiple groupby charts

[jertel]

Given a dashboard with the following query:

* | groupby -sankey event.dataset event.category* | groupby -pie event.category | groupby -bar event.module* | groupby event.dataset | groupby event.module* | groupby event.category | groupby observer.name | groupby source.ip | groupby destination.ip | groupby destination.port | groupby destination_geo.organization_name

Clicking one of the bars on the event.module bar chart brings up a Quick Action menu with links pre-populated with the wrong field. So if you click Include, it will add a filter for the event.dataset field instead of the event.module field.

The incorrect code is located in hunt.js::handleChartClick(), specifically this line that assumes to use the first field of the first graph:

            var chartGroupByField = this.groupBys[0].fields[0];

[dougburks]

Tested and verified: