performance-metrics: Move some helper functions to test_infra

The helper functions for measuring and parsing the performance of
virtio-net and virtio-block devices are moved to the `test_infra` crate
so that they be reused for integration tests of rate limiter.

Signed-off-by: Bo Chen <chen.bo@intel.com>

performance-metrics/src/main.rs

@@ -20,6 +20,7 @@ use std::{
     thread,
     time::Duration,
 };
+use test_infra::FioOps;
 use thiserror::Error;
 
 #[derive(Error, Debug)]