forEachChunk(_:)

Drives the read loop for you, calling body with each chunk of the request body. This is what most streaming handlers want; it is a convenience over withReader(_:) and shares its semantics with forEachChunk(_:) (borrowed span, valid only for the call — copy out anything you keep).

consuming func forEachChunk(_ body: (Span<UInt8>) async throws -> Void) async throws