HPCC-10576 Add code to roxie to call Thor graphs

Copy code from hthor (rather than commoning up) since intention is to remove
the hthor version at some point

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #5250 from richardkchapman/roxie-thor

HPCC-10576 Add code to roxie to call Thor graphs

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>