Feature: Split Flamegraphs per Unit Test/Bench

[AlexandreCassagne]

Is it feasible as it stands, or is it possible to implement a segregation of the perf data into multiple flamegraphs, for example one per unit test or one per benchmark?

This would be useful as a set of CI artefacts and could pave the way to per-test/per-bench perf diffing, without running cargo flamegraph multiple times (which has overhead).

[djc]

I am currently passively maintaining flamegraph -- if you'd like to have functionality like this, I'm happy to review a PR and/or try to answer any questions you might have on how to fit it into the existing code base.