Warmup counts cfg

[twharmon]

I noticed that in webdriver-ts/src/common.ts the config const contains the number of warm-up runs, but the partial update cpu benchmark does not use that number and instead uses a hard-coded 3.

Should we move the warm-up count from the shared config into the cpuBenchmarkInfosArray in webdriver-ts/src/benchmarksCommon.ts? This makes it so that the number of warm-ups for each benchmark can be individually configured (similar to how the number of additional timed runs is configured).

A few more changes had to be made to accommodate this, so you see changes in the BenchmarkInfoBase type definition. I did my best to make sure that the final description of each cpu benchmark stays exactly as it was before.