fio: Add flags to capture latency, bandwidth and IOPS logs
fio: Add flags to capture latency, bandwidth and IOPS logs

Add the ability to optionally collect the latency, bandwidth and IOPS logs
for a fio job. This is also include the flag fio_log_avg_msec that averages
the log entries over the given interval.

meteorfox/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker,meteorfox/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker