Add support for dynamic objects in Aggregate and Group by fields

[andresmgot]

I noticed that dynamic values cannot be used for the summarize function (used for the Aggregate and Group by fields). For aggregating, I am converting the value to a long since its goal is to be used with a mathematical function. For grouping I am converting the value to a string. Note that the goal of this is not to support all the possible use cases but to at least give valid syntax:

Aggregate example:

Group by example:

I tried to do some unit test for this but it seems that the current components are not working with the react testing library (clicking on the "+" button didn't render the selector). I could do some e2e test for covering this functionality but it doesn't seem worth it. Let me know what you think.

[github-actions]

Code coverage report for PR #390

	Go	TypeScript
main	54.5%	60.86%
PR	54.5%	62.81%
difference	0%	1.95%

[aangelisc]

LGTM! Just a minor question.

I'm happy with leaving the e2e test out as I agree it will be excess work for little gain. I think opening a separate ticket to investigate why the unit tests don't work as expected is probably a better course of action. Once that's solved we can unit test accordingly 👍

[andresmgot]

I think opening a separate ticket to investigate why the unit tests don't work as expected is probably a better course of action. Once that's solved we can unit test accordingly

I think we should actually reduce the amount of time invested in supporting the current query builder. Instead, we should try to focus our efforts on using a generic query builder, like the one that is exposed now in the @grafana/experimental package. I have created a new issue / epic to track this effort: #391