message: identity: Add more details to the OS_INFO metrics
  This commit extends the OS_INFO prometheus metric to add the
  basearch, stream and platform information.
  The final metrics looks like :
  ```
  zincati_identity_os_info{basearch="x86_64",os_version="32.20200629.3.0",platform="qemu",stream="stable"} 1
  ```
  Fixes
diff: @@ -25,7 +25,7 @@ lazy_static::lazy_static! {
  static ref OS_INFO: IntGaugeVec = register_int_gauge_vec!(
  "zincati_identity_os_info",
  "Information about the underlying booted OS",
  - &["os_version"]
  + &["os_version", "basearch", "stream", "platform"]
  ).unwrap();
  }
  @@ -72,7 +72,14 @@ impl Identity {
  }
  // Export info-metrics with details about booted deployment.
  - OS_INFO.with_label_values(&[&id.current_os.version]).set(1);
  + OS_INFO
  + .with_label_values(&[
  + &id.current_os.version,
  + &id.basearch,
  + &id.stream,
  + &id.platform,
  + ])
  + .set(1);
  Ok(id)
  }
  