Sample code for RFC transport

As this now supports pluggable HTTP clients, we can call the API over RFC as eclipse does.

This is based on node-rfc which requires SAP NW RFC SDK to be installed.
Installation instructions can be found in its home page. I believe you'll need a SAP S-user to obtain it.

instructions

This only supports logging in a single app server with username and password
The node-rfc documentation covers other cases

To run the sample code install the dependencies by running in this folder:

``bash
npm i
`

If this is successful (requires the SAP NW RFC SDK to be installed) run:

`bash
npx ts-node callwithrfc.ts myappserver 00 myuser mypass
`

Of course you'll need to replace the server details with your own

You will get something like:

`javascript
Direct HTTP call:
{
body: 'X',
headers: {
'~server_protocol': 'HTTP/1.1',
ETag: '201502131923270014',
'Last-Modified': 'Fri, 13 Feb 2015 19:23:27 GMT',
'Content-Type': 'application/vnd.sap.adt.programs.programs.v2+xml; charset=utf-8'
},
status: 200,
statusText: 'OK'
}

Client API call:
{
objectUrl: '/sap/bc/adt/programs/programs/SAPMCRFC',
metaData: {
'program:lockedByEditor': false,
'program:programType': 'modulePool',
'abapsource:sourceUri': 'source/main',
'abapsource:sourceObjectStatus': 'system',
'abapsource:fixPointArithmetic': true,
'abapsource:activeUnicodeCheck': true,
'adtcore:responsible': 'SAP',
'adtcore:masterLanguage': 'DE',
'adtcore:masterSystem': 'SAP',
'adtcore:name': 'SAPMCRFC',
'adtcore:type': 'PROG/P',
'adtcore:changedAt': 1423855407000,
'adtcore:version': 'active',
'adtcore:createdAt': 1097625600000,
'adtcore:changedBy': 'SAP',
'adtcore:description': 'Display and Edit RFC Destinations',
'adtcore:descriptionTextLimit': 70,
'adtcore:language': 'EN'
},
links: [
{
href: 'source/main/versions',
rel: 'http://www.sap.com/adt/relations/versions'
},
{
href: 'source/main',
rel: 'http://www.sap.com/adt/relations/source',
type: 'text/plain',
etag: '201502131923270011'
},
{
href: 'source/main',
rel: 'http://www.sap.com/adt/relations/source',
type: 'text/html',
etag: '201502131923270011'
},
{
href: '/sap/bc/adt/vit/wb/object_type/progpx/object_name/SAPMCRFC',
rel: 'http://www.sap.com/adt/relations/sources/textelements',
type: 'application/vnd.sap.sapgui',
title: 'Text Elements'
}
]
}
``