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)));

#webservice(fields('u1', 'i1', 'u2', 'i2', 's1'), help("Fill in values"),
description("does cool stuff"));

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
I would prefer not to keep extending the grammar with the specific attributes that are allowed by something like this.  I think you can use hintItem/hintList to allow an arbitrary list, but then post process it to pick out the options you want.  It helps avoid making even more reserved keywords, and doesn't require grammar changes when new options are supported.

Same goes for storedFieldFormatOpts.