performance-metrics: Generate a summary report in Json

The report contains the test results with commit hash and date.

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

performance-metrics/Cargo.toml

@@ -3,6 +3,7 @@ name = "performance-metrics"
 version = "0.1.0"
 authors = ["The Cloud Hypervisor Authors"]
 edition = "2018"
+build = "build.rs"
 
 [dependencies]
 dirs = "4.0.0"
@@ -12,3 +13,6 @@ serde_derive = "1.0.136"
 serde_json = "1.0.78"
 test_infra = { path = "../test_infra" }
 wait-timeout = "0.2.0"
+
+[build-dependencies]
+clap = { version = "3.0.14", features = ["wrap_help"] }