Report standard deviation in benchmarks

[Akirathan]

Our benchmark charts currently displays only score which is an average of one benchmark iteration in milliseconds.

Since JMH can, and does, output stddev, it would be nice to:

### Tasks
- [ ] Make sure stddev is saved in the XML generated by the JMH benchmark runner
- [ ] Make sure that this stddev is displayed in the charts, if present in the XML artifact.

stddev is a very important metric as it tells us basically how much we can trust the results for a particular benchmark.

[radeusgd]

As noted, the std-dev allows us to easier differentiate benchmarks like the navy vs orange ones from this analysis (one has very high variance and the other is very 'stable').

[radeusgd]

Just a note that in #8091 I added displaying stdev within the Enso runner for the benchmarks. This is a bit perpendicular, because this is not the runner used on CI so the ticket remains open - but it is slightly related so I thought it may be worth noting.

[radeusgd]

We can see how the stdev allows us to better judge the benchmarks - for example the high stdev in the Enso variants may show that the warmup time is insufficient and should be made larger if we want to see the peak performance.