Benchmarks: generate heap profiles

[pepeiborra]

The heap profiles are generated using +RTS -h and rendered using http://hackage.haskell.org/package/eventlog2html
The artefact tree for a given example&experiment looks as follows:

ghcide/bench-results/Cabal-3.0.0.0/upstream/
├── completions_after_edit.benchmark-gcStats
├── completions_after_edit.csv
├── completions_after_edit.diff.svg
├── completions_after_edit.eventlog                # new
├── completions_after_edit.eventlog.html           # new
├── completions_after_edit.hp                      # new
├── completions_after_edit.log
├── completions_after_edit.svg

Other changes:

• Fix a bug (introduced in Benchmark improvements #1178) affecting the live bytes svg diagrams.
• Enable Shake parallelism for the benchmark rules (the benchmarks themselves are guarded by a Shake resource so there's only one ghcide process running at a given time)

[ndmitchell]

Sweet!

[wz1000]

Is there a way to view the results recorded by CI? I can't see the eventlog2html output in the CI artifacts.

[pepeiborra]

Oh, I forgot to update the Github action :(

[pepeiborra]

#1254