Allow Flower prometheus metrics to be grouped by distinct values of a specified task arg

[dpdoughe]

Is your feature request related to a problem? Please describe.
I would like to further group Grafana dasbhoard by a string kwarg that is sent to (some) of my Celery tasks to be evaluated. This string can only take on 4 distinct values. I'd like to dashboard separately things like "Task Success Ratio", "Number of Tasks Currently Executing at Worker", "Average Run Time at Worker", "Task Prefetch Time at Worker", "Number of tasks Prefetched at Worker", and "Task failure ratio". Currently my dashboard is just lumping these all together. This is OK, but I'd also like to see that tasks that have this kwarg be able to calculate or aggregate separately by the value of this kwarg. If the particular arg is not sent to a task I think it would be acceptable to aggregate those into a single group.

Describe the solution you'd like
Could a grouping variable be identified by argument name be used to group the available metrics ? Then could Prometheus and Grafana group or aggregate dashboarding within those distinct values of the grouping arg?