HPCC-9712 Add optimized proxy mode to WsECL for roxie

SOAP and JSON requests for roxie sent to WsECL should be treated as
pass through operations, and URL and form submissions will have a
new mode that doesn't use the workunit/schema for pre or post
processing.  To use this mode replace "submit" in the URL with
"proxy".

Signed-off-by: Anthony Fishbeck <Anthony.Fishbeck@lexisnexis.com>
Merge pull request #4664 from afishbeck/wseclProxyMode9712

HPCC-9712 Add optimized proxy mode to WsECL for roxie

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>