HPCC-11615 Add some timing info to file copy tracing

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #6020 from richardkchapman/roxie-file-copy-stats

HPCC-11615 Add some timing info to file copy tracing

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>