crypto/tls: expose HelloRetryRequest state

crypto/tls: expose HelloRetryRequest state

This commit adds fields to the ClientHelloInfo and ConnectionState
structures to represent hello retry request state information.

ClientHelloInfo gains a new HelloRetryRequest bool field that indicates
if the client hello was sent in response to a TLS 1.3 hello retry
request message previously emitted by the server.

ConnectionState gains a new HelloRetryRequest bool field that indicates
(depending on the connection role) whether the client received a TLS 1.3
hello retry request message from the server, or whether the server sent
such a message to a client.

Fixes #74425

Change-Id: Ic1a5290b8a4ba1568da1d2c2cf9f148150955fa5
Reviewed-on: https://go-review.googlesource.com/c/go/+/717440
Reviewed-by: Roland Shoemaker <roland@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Daniel McCarney <daniel@binaryparadox.net>