Builtin feature to run ligthouse multiple times and get the median result

[becheran]

I would love to have the ability to run ligthouse multiple times builtin and simply pass an n variable or something like this to the measurement. Insteead of returning the report of one run, it could then use the median of multiple runs.

This is also a recomended strategy described and recomended by google: https://github.com/GoogleChrome/lighthouse/blob/main/docs/variability.md#run-lighthouse-multiple-times

It would not be dificult to add this function without breaking the existing interface. What do you think?