"Spec" compliance

[armanbilge]

I'm using "spec" here very loosely 😅 in order of specy-ness:

1. https://spec.graphql.org/June2018/
2. https://github.com/graphql/graphql-over-http/blob/main/spec/GraphQLOverHTTP.md
3. https://github.com/enisdenjo/graphql-ws/blob/master/PROTOCOL.md
   Note that apollographql/subscriptions-transport-ws is archived and points to there instead.
4. https://github.com/enisdenjo/graphql-sse/blob/master/PROTOCOL.md

I still have a lot of reading to do since I'm new to GraphQL. Some of my notes so far:

• the client interfaces for query/mutation/subscription should use only concepts from (1); e.g. the core model should not be tied to the http spec or notions of persistent connections. It seems ok to use circe.Json as an intermediary format since that's pretty close to what the spec describes
  

  clue/model/src/main/scala/clue/model/GraphQLRequest.scala

  Line 9 in 7fb6240

  // Request format from Spec: https://github.com/APIs-guru/graphql-over-http

• backends for these clients should probably be implemented directly in terms of http4s (ws-)clients according to (2), (3), (4); this does not rule out common abstractions for sharing of code, but it seems like that should remain an internal implementation detail since these specs may evolve independently
• special functionality to reconnect/recreate subscriptions sounds like middleware territory to me