HPCC-8799 Add WsEcl for JSON via HTTP GET and FORM-ENCODED-POST

An HTTP GET or application/x-www-form-urlencoded POST to a URL
of the format:  /WsEcl/submit/query/<target>/<queryid>/json will
return an application/json formatted response.

For HTTP-GET requests stored paramters can be passed as URL
parameters:

/WsEcl/submit/query/<target>/<queryid>/json?stored1=abc&stored2=33

Signed-off-by: Anthony Fishbeck <Anthony.Fishbeck@lexisnexis.com>