Improve the accuracy of Histogram in client metric

The Histogram type (org.apache.kafka.common.metrics.stats) in KafkaMetrics in the client module statically divides the value space into a fixed number of buckets and only returns values on the bucket boundary. So, the returned histogram value may never show up in a recorded value. Yammer Histogram, on the other hand, uses reservoir sampling. The reported value is always one of the recorded values, and is likely more accurate. Because of this, the Histogram type in client metric hasn't been used widely. It would be useful to improve Histogram in the client metric to be more accurate.