HPCC-9917 Add webservice options to ECL

Add new FORMAT specifiers to STORED to affect field formatting and
sequence.

Add new #WEBSERVICE function for options affecting webservice.
Support explicit selection and ordering of specific fields.  Support
adding help and descriptive text.

Usage:

unsigned2 u1 := 0 : stored('u1', few, format(fieldwidth(8), sequence(12)));
integer2 i1 := 0 : stored('i11, format(fieldwidth(9), sequence(11)));

description("does cool stuff"));

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
Merge pull request #6742 from afishbeck/webserviceEcl

HPCC-9917 Add webservice options to ECL

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>