fix(s2n-quic-transport): optimize STOP_SENDING state

[camshaft]

Description of changes:

When entering the STOP_SENDING state in the receive stream, we currently wait for the peer to either finish transmitting all outstanding data or send a RESET frame. This isn't really needed since the application has already indicated that it's not going to read any more data.

This change, instead, marks the stream as finalized when the STOP_SENDING frame is ACKed. Any additional frames that are received will be ignored:

s2n-quic/quic/s2n-quic-transport/src/stream/stream_manager.rs

Lines 807 to 813 in 222a807

	// If the Stream does not exist it is no error.
	state
	.streams
	.with_stream(stream_id, &mut state.stream_controller, |stream| {
	func(stream, &mut events)
	})
	.unwrap_or(Ok(()))

Testing:

I've updated all of the receive stream unit tests to reflect the new behavior.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.