* http3: implement server idle timeout support
This update introduces the ability for an HTTP/3 server to enforce an idle
timeout on connections. This timeout will trigger when no new requests are
received on a connection, irrespective of any PING frames received at the
QUIC level.
* fix deadlock when http3 idle timeout is not enabled
* fix typo
* Switch to a more efficient implementation
* Avoid a goroutine
* Avoid constent re-adjusting of a timer
* Works with hijacked streams
* Generalize the idle timeout description
* Add an integration test for http server idle timeout
* Attempt to fix other tests impacted by the new idle timeout test
The stream exposes two methods required for doing an HTTP request:
SendRequestHeader and ReadResponse. This can be used by applications
that wish to use the stream for non-HTTP content afterwards. This will
lead to a simplification in the API we need to expose for WebTransport,
and will make it easier to send HTTP Datagrams associated with this
stream.
