Add more timeAuditMetrics or new Audit Values graph

[mintyfloss]

This exporter has been really helpful for us to track our page performance. Sometimes it's difficult for us to determine why our performance score changes. Is it possible to add more metrics like TTFB or main-thread work to timings?

I see that in the Audit Scores section there is time-to-first-byte score. It's possible that our score remains at 1.0 but the actual value of TTFB drops. Instead of adding more metrics to the Timings graph, just having Audit Values graph would be very helpful for us. Is that possible too?