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>
this sort will probably reorder fields that do not have a sequence attribute.  Is that problem  - or is it generally completely undefined?  Do you also need something to preserve the original order?  (Should it sort alphabetically so it is at least semi consistent??)