Pause before close to avoid TIME_WAIT

[rossabaker]

Maybe a bit off-topic for this PR, but when returning a Connection: close do you pause before closing to allow the client to do an active close avoiding TIME_WAIT on the server side?

Originally posted by @milessabin in #913 (comment)

[rossabaker]

I haven't researched this yet, but Section 9.6 of RFC 9112 is probably what we want to do.

[milessabin]

IIRC shutdownOutput in Socket/SocketChannel were introduced to support exactly this scenario.