HPCC-12282 Simplify stats definitions so all done in one place

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-12282 Implement statistics gatherer that updates a workunit

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-12282 Move roxie global stats into new mechanism

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>