HPCC-10409 Provide functions to access user/system time

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-10409 Fix issues picked up in code review

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #5139 from ghalliday/issue10409

HPCC-10409 Provide functions to access user/system time

Reviewed-By: Jake Smith <jake.smith@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>