HPCC-9085 Fix Roxie JSON handling of array item names

Simple arrays (ECL Sets) will no longer output names for items in
the array.  Also nested children with same name as array ancestor
will not be treated as array items.

Signed-off-by: Anthony Fishbeck <Anthony.Fishbeck@lexisnexis.com>
HPCC-9085 Improve method names and remove unneeded IMPLEMENT_IINTERFACE

Signed-off-by: Anthony Fishbeck <Anthony.Fishbeck@lexisnexis.com>
Merge pull request #4211 from afishbeck/json_array_itemnames

HPCC-9085 Fix Roxie JSON handling of array item names

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>