HPCC-12481 Add peak memory usage for the compile phase to wu stats

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #6677 from ghalliday/issue12481

HPCC-12481 Add peak memory usage for the compile phase to wu stats

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>