make resolved/resolvedWhen useful for experiments
in !12 (merged), I noticed that we can't quite change the severity of an experiment or mark it as resolved as we typically do with other issues.
it would be nice if we could use the same workflow than other issues. in !12 (merged), for example, it would this part irrelevant:
## When did it stop? -Not yet, it's still ongoing as far as we know. +Around 2021-09-08 13:00:00 UTC.
which would be less error-prone.