Offer Structured Concurrency conforming APIs for response streaming

[weissi]

Motivation

At the moment, the generator generates functions that violate Structured Concurrency for things that use HTTP response streaming. The user gets returned an async sequence that they are then supposed to stream and until that's done resources in other tasks/threads are still holding onto the live request.

This is of course violates the main principle of Structured Concurrency which is that upon return of a function, the execution resources it acquired have been released back.

Violating Structured Concurrency might be acceptable in certain cases but:

1. It should be documented that what's going on (Document Structured Concurrency violating functions #727)
2. An alternative should be offered (such as try await withFooRequest(parameters: Parameters) { result, responseBodyStream in ... }) [this feature request]

This feature request part (2), the additional availability of a fully structured API that does response streaming.

Similar efforts in other projects:

• document known Structured Concurrency violations swift-nio#3108
• baby steps towards a Structured Concurrency API swift-server/async-http-client#806
• offer Structured Concurrency API that supports HTTP response streaming swift-server/async-http-client#807

Proposed solution

Offer properly structured APIs that support HTTP response streaming in a with* function.

Alternatives considered

No response

Additional information

No response