Ensure that HttpResponse.BodySubscribers.ofFile writes all bytes

The implementation of PathSubscriber should ensure that all bytes from the given buffers are written. Specifically, this method in PathSubscriber:

@Override
public void onNext(List<ByteBuffer> items) {
    try {
        out.write(items.toArray(Utils.EMPTY_BB_ARRAY));
...

the implementation assumes out.write(ByteBuffer[]) always writes the content of all buffers - this isn't the case and the method can write a lesser number of bytes from input buffers.

See https://mail.openjdk.org/pipermail/net-dev/2022-December/019883.html