Add a graph of per-crate geometric means to the homepage

[anp]

It would be great to have an instant visual representation of the state of rust perf over time.

[lqd]

Another interesting datapoint in the same spirit, would be to also track the state of rust perf between releases in addition to nightlies. It would be interesting to show possible improvements/regressions at these milestones (or maybe also show slowly moving trends where the variance would stay for a long time "under the daily anomaly alert threshold" — if that's even possible, I don't know how lolbench detects those :)

Perf.rlo has a similar feature in the form of a dashboard.

That being said, if the data is similar to perf.rlo's dashboard, where the changes are not huge between releases, maybe "for each release" is too fine of a granularity.

(cc @ekleog who asked about this)