HPCC-12370 Improve timing display and support merging statistics

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-12370 Changes to javascript following review comments

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #6517 from ghalliday/issue12370

HPCC-12370 Improve timing display and support merging statistics

Reviewed-By: Gordon Smith <gordon.smith@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>