@defer: support in JS HttpEngines

[BoD]

When using @defer the expectation is that the deferred parts are surfaced as soon as they arrive.

However the current JS and Apple DefaultHttpEngine implementations buffer the whole response before returning it, making all the parts emitted only after the last one has been received.

[BoD]

• Apple implementation is ✅ in a specific HttpEngine (caveat: it requires the new memory model), in Chunked support on Apple in specific HttpEngine #4073
• JS implementation is based on KTOR, which JS implementation currently doesn't support streaming, even though the generic API allows it. See this issue.

[jpvajda]

@martinbonnin I noticed this issue in Todo for @defer Will we make this change as a follow up release?

[martinbonnin]

@jpvajda ideally we'd wait for KTOR to implement the feature before adding it in Apollo Kotlin. If it becomes too much of an issue for us, we could consider contributing the fix there. (the feature being the ability to receive HTTP chunks as they arrive)

[jpvajda]

@martinbonnin sounds good! we can discuss what release to put this in in our sync today.

[jpvajda]

We discussed this today and we'll wait to see the resolution on this dependency https://youtrack.jetbrains.com/issue/KTOR-4274/HttpClient-Streaming-support-in-JS.