[pm/metrics] add apk size in the log

Sum up all apk sizes in the code path and record in the log.

Test: atest android.content.pm.cts.PackageManagerShellCommandTest#testSplitsInstallStdIn
Test: out/host/linux-x86/bin/statsd_testdrive 263
event_metrics {
  data {
    elapsed_timestamp_nanos: 1543983836620
    atom {
      package_installer_v2_reported {
        is_incremental: true
        package_name: ""
        duration_millis: 327
        return_code: 1
        size: 2512345
      }
    }
  }
}
BUG: 152913040
Change-Id: Idde0adb6b639163627c092ed248631edfba2e952

Change-Id: I0eaf226513ee5a1b5f73726f4480c6ee73210b0d