Feature: Add separate groupBy field for different metrics in Explorer visualisation

[cseas]

Use Case

As a user, I'm trying to add separate groupBy filters for the different metrics I've added to the Explorer visualisation.

Proposal

Add a separate groupBy input field for each component. Or add an information tooltip next to the single groupBy field that indicates the single field works for all metrics added.

Questions to address (if any)

The groupBy field doesn't get replicated like the other fields when we add a new metric. So it's not clear whether the groupBy applies to all the metrics or just the first one. If a single groupBy field is to be kept for all the metrics, then some information should be provided indicating how it works.