Chart Value Actions Usability Improvements

## The Problem

There are a couple of things we should do to improve the chart value actions, as results from testing:

After clicking a value, the first popover shows a breakdown of the value's metric + value and groupings key + value pairings:

The prototypical use case for this would be: A user clicks on a slice in a pie chart, wanting to drill down to the documents that match it, either by showing them in a message table (`Show documents for value`) or filter to them (`Add to query`). (As a sidenote, would it make sense to be able to create a new aggregation widget from here, pre-filtered to the values?)

The problems with this are:

1.) Especially for the pie chart, the user cannot perform an action on the sum of the groupings pairs, like showing documents that constitute the values for this slice.
2.) Performing actions on individual groupings pairs mostly make no sense.
3.) Metrics shown in here often cannot be used with most actions, because they might have no direct representation in the data (like for `avg`, `card`, `percentile`, `count`).
4.) For timeline charts, the `timestamp` value is taken as a singular point, but it actually is a range (of the bucket in this aggregation). Operating on it should transform this from a timestamp to a time range.

## The solution

The suggestions for improvement are:

- Do not show the initial popover, but open the actions popover for the _sum of all groupings pairs_ immediately.
- Do not take metrics into account.
- If a time-based grouping field is used, expand it into a range instead of a singular value.
- (**Optional**) Allow deselecting individual groupings pairs from the header of the actions popover.