Benchmark tracing performance

[shuhaowu]

• [x] Emit latency (min, avg, max, p99) and throughput (max emit per second).
• [ ] TraceAggregator throughput: need to understand the impact of serializing the data and also file write performance
  • Can use a "test sink" that doesn't write to file to test for CPU overhead.
• [ ] Data rate: need to know the data size per event which can be used to extrapolate IO rates when writing data to sinks. Compare results with when string interning is implemented.