HPCC-10149 Optimize JOIN(l,r,...,t(LEFT),ATMOST(1),LEFT OUTER)

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-10149 More tests, and don't optimize KEEP(1),LIMIT(n)

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-10149 Fix regression test, and check for KEEP(1), LIMIT(n)

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #4925 from ghalliday/issue10149

HPCC-10149 Optimize JOIN(l,r,...,t(LEFT),ATMOST(1),LEFT OUTER)

Reviewed-By: Jamie Noss <james.noss@lexisnexis.com>
Reviewed-By: Jake Smith <jake.smith@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>