[zetracer] Report median time

[dmitriy-sobolev]

Hi,

It would be great to have median metric alongside with average or have a choice. Many benchmarks run warm-up trials and then a lot of main trials of the same workload. Having median is useful to exclude spikes which usually happen during warm-up runs.

I refer to the Average metric from an example report below:

=== API Timing Results: ===

Total Execution Time (ns):    418056422
      Total API Time (ns):    407283268

                         Function,       Calls,     Time (ns),  Time (%),     Average (ns),      Min (ns),      Max (ns)
        zeCommandQueueSynchronize,           4,     182529847,     44.82,         45632461,      45271728,      46364532
                   zeModuleCreate,           1,     111687828,     27.42,        111687828,     111687828,     111687828
zeCommandQueueExecuteCommandLists,           4,     108593458,     26.66,         27148364,       1756304,     102803947
    zeCommandListAppendMemoryCopy,          12,       2493748,      0.61,           207812,         62061,       1037087