HPCC-8554 Combine derived helpers that are split into multiple interfaces

Clean up some helpers that were split purely for back-compatibility reasons.
Once that are split for logical functionality reasonas have been left.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #4007 from richardkchapman/eclhelper-cleanup-1

HPCC-8554 Combine derived helpers that are split into multiple interface...

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>