HPCC-10276 Add jsonp support to WsEcl

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
Merge pull request #5050 from afishbeck/wsecl_jsonp10276

HPCC-10276 Add jsonp support to WsEcl

Reviewed-By: Gordon Smith <gordon.smith@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>