Add the structure for generating and writing qlog events.

Events are generated as slog events using the structure of
the qlog events (draft-ietf-quic-qlog-quic-events-03).

The qlog package contains a slog Handler implementation
that converts the quic package events to qlog JSON.

This CL generates events for connection creation and closure.
Future CLs will add additional events.

Events follow draft-ietf-quic-qlog-quic-events-03, which
is the most recent draft supported by the qvis visualization
tool.

https://www.ietf.org/archive/id/draft-ietf-quic-qlog-main-schema-04.html
https://www.ietf.org/archive/id/draft-ietf-quic-qlog-quic-events-03.html

For golang/go#58547

Change-Id: I5fb1b7653d0257cb86726bd5bc9e8775da74686a
Reviewed-on: https://go-review.googlesource.com/c/net/+/537936
Auto-Submit: Damien Neil <dneil@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

Negotiate the connection idle timeout based on the sent and received
max_idle_timeout transport parameter values.

Set a configurable limit on how long a handshake can take to complete.

Add a configuration option to send keep-alive PING frames to avoid
connection closure due to the idle timeout.

RFC 9000, Section 10.1.

For golang/go#58547

Change-Id: If6a611090ab836cd6937fcfbb1360a0f07425102
Reviewed-on: https://go-review.googlesource.com/c/net/+/540895
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

Do not commit data written to a stream to the network until
the user explicitly flushes the stream, the stream output
buffer fills, or the output buffer contains enough data to
fill a packet.

We could write data immediately (as net.TCPConn does),
but this can require the user to put their own buffer in
front of the stream. Since we necessarily need to maintain
a retransmit buffer in the stream, this is redundant.

We could do something like Nagle's algorithm, but nobody
wants that.

So make flushes explicit.

For golang/go#58547

Change-Id: I29dc9d79556c7a358a360ef79beb38b45040b6bc
Reviewed-on: https://go-review.googlesource.com/c/net/+/543083
Auto-Submit: Damien Neil <dneil@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

The name Listener is confusing, because unlike a net.Listener
a quic.Listener manages outgoing connections as well as inbound ones.

Rename to "endpoint" which doesn't map to any existing
net package name and matches the terminology of the QUIC RFCs.

For golang/go#58547

Change-Id: If87f8c67ac7dd15d89d2d082a8ba2c63ea7f6e26
Reviewed-on: https://go-review.googlesource.com/c/net/+/543298
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

Separate from CL 543298 to help git recognize that this is a rename.

Change-Id: I1cbdffeb66d0960c951a564b8fc1a3dcf2cf40f6
Reviewed-on: https://go-review.googlesource.com/c/net/+/543299
Reviewed-by: Jonathan Amsterdam <jba@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Update golang.org/x dependencies to their latest tagged versions.

Change-Id: Ia3b446633ffc0b3264692cfaae765bfb79063dab
Reviewed-on: https://go-review.googlesource.com/c/net/+/545175
Auto-Submit: Gopher Robot <gobot@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>