HPCC-10494 Make WsEcl REST query responses use specified format

Exceptions were not respecting the format specified in the URL.

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
Merge pull request #5627 from afishbeck/wseclExceptionFormatting

HPCC-10494 Make WsEcl REST query responses use specified format

Reviewed-By: Gordon Smith <gordon.smith@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>