Add a way to access response headers about swift-graphql

[matthewspear]

+1 = I have a usecase where each query an anti-crsf token is being set on the response headers and I need easy access to it.

[maticzav]

👋

The new version let's you take complete control over how you send and receive your request. Instead of hiding the networking part, the library's core (the whole library in the previous version) only handles selection and decoding. You can find the methods that (I think) you are looking for in https://github.com/maticzav/swift-graphql/blob/main/Sources/SwiftGraphQL/HTTP.swift.

Feel free to reopen this issue or add comments if you need more help 🙂