HPCC-10579 Improve many lookup join implementation in roxie

Similar concept to the thor improvements in HPCC-9244, which can dramatically
improve performance on pathogenic cases that have many dups on RHS.

Should not slow down other cases (though may increase memory usage a little).

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
HPCC-10579 Improve many lookup join implementation in roxie

Minor changes following code review

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
HPCC-10579 Improve many lookup join implementation in roxie

Additional refactoring following code review, and fix the stable sort version.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
HPCC-10579 Improve many lookup join implementation in roxie

Add a simple test case.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #5579 from richardkchapman/roxie-many-lookup

HPCC-10579 Improve many lookup join implementation in roxie

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>