Add Nodes for building and executing GraphQL requests

Hello!

First, I’d like to say thanks for creating this library. It’s been a tremendous help in our integration tests and we really love using it!

Opening this PR for discussion on a feature request to incorporate Nodes as part of the framework so that testing GraphQL APIs can be even easier!

For example, https://github.com/intuit/karate/blob/master/karate-demo/src/test/java/demo/graphql/graphql.feature could end up looking something like

Scenario: simple graphql request
    Given request read('classpath:models/Pokemon.java')
    When method query
    Then status 200

just a quick stab at it - more thoughts on it once I dig into implementation further

Then the output will also be mapped to the Pokemon model and more features can be added around checking the properties there

[chemdrew]

Thanks for pointing all this out! More thoroughly read all the documentation and see the multiple references to preferring JSON to POJOs.

As an initial starting point I was able to make both libraries play together very nicely here https://github.com/chemdrew/karate/commit/34eb41184d3aba5c2a9f3f04a8e723ac714f1301

I’ll also be taking a closer look at generating from JSON. I was actually playing with the idea of making a Javascript version of Nodes that followed the same pattern with a very similar API but constructing the queries from JSON, might be moving that up in my todo list 😄

[ptrthomas]

closing - and can re-open if needed in the future