Fixes Encoded JSON Result Ordering

[NeedleInAJayStack]

If you encode a GraphQLResult with an ordinary JSONEncoder, there are no guarantees that the field order will match the query, violating the GraphQL spec.

This PR adds a GraphQLJSONEncoder type that will ensure that order is preserved when a Map is encoded. It is exactly the same as Foundation's JSONEncoder, but uses OrderedDictionary everywhere Dictionary was used.

[NeedleInAJayStack]

I don't love duplicating so much code from Foundation but I couldn't think of another easy way to get this level of access to the base JSONEncoder class and I hesitated to make a PR to Foundation or swift-collections because our needs seem like an unusual edge-case.

However, if you have any thoughts on how to minimize copied code I'm interested in hearing them!

[paulofaria]

The ideal solution would be to add an option to Foundation's JSONEncoder, like the pretty print option API. However, that would take a while and it's not even guaranteed that they would accept it. So I guess it makes sense for us to provide the appropriate encoder ourselves. I'm refactoring Graphiti to add support for async await and ended up getting carried away and decided to update a lot of APIs. This would mean a major bump and now I'm thinking we might rename Map to JSON, since that's basically what it is. While doing that, we could just update MapEncoder to use ordered dictionaries (if it doesn't already, I have to look). What do you think?

[NeedleInAJayStack]

The ideal solution would be to add an option to Foundation's JSONEncoder, like the pretty print option API. However, that would take a while and it's not even guaranteed that they would accept it. So I guess it makes sense for us to provide the appropriate encoder ourselves.

I agree on both counts.

I'm thinking we might rename Map to JSON, since that's basically what it is. While doing that, we could just update MapEncoder to use ordered dictionaries (if it doesn't already, I have to look).

It does already, since #84. Interestingly, that one preserved result ordering throughout the query -> GraphQLResult process, but I was getting randomized order at the final step when encoding GraphQLResult to JSON, prompting this PR.

What do you think?

I think this all sounds awesome! Nice work attacking the async/await transition!

[NeedleInAJayStack]

Hey @paulofaria, do you have any other concerns on this? Do you mind approving if not?

[paulofaria]

Sorry for the delay!