HPCC-8518 Optimize JOIN(transform(LEFT),LEFT OUTER,LOOKUP) to PROJECT

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #3833 from ghalliday/issue8518

HPCC-8518 Optimize JOIN(transform(LEFT),LEFT OUTER,LOOKUP) to PROJECT

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>