Add the SSL_METHOD for TLSv1.3 and all other base changes required

Includes addition of the various options to s_server/s_client. Also adds
one of the new TLS1.3 ciphersuites.

This isn't "real" TLS1.3!! It's identical to TLS1.2 apart from the protocol
and the ciphersuite...and the ciphersuite is just a renamed TLS1.2 one (not
a "real" TLS1.3 ciphersuite).

Reviewed-by: Rich Salz <rsalz@openssl.org>

apps/s_server.c

diff --git a/apps/s_server.c b/apps/s_server.c
index d32b9df..24841c5 100644
--- a/apps/s_server.c
+++ b/apps/s_server.c
@@ -669,7 +669,7 @@
     OPT_NO_RESUME_EPHEMERAL, OPT_PSK_HINT, OPT_PSK, OPT_SRPVFILE,
     OPT_SRPUSERSEED, OPT_REV, OPT_WWW, OPT_UPPER_WWW, OPT_HTTP, OPT_ASYNC,
     OPT_SSL_CONFIG, OPT_SPLIT_SEND_FRAG, OPT_MAX_PIPELINES, OPT_READ_BUF,
-    OPT_SSL3, OPT_TLS1_2, OPT_TLS1_1, OPT_TLS1, OPT_DTLS, OPT_DTLS1,
+    OPT_SSL3, OPT_TLS1_3, OPT_TLS1_2, OPT_TLS1_1, OPT_TLS1, OPT_DTLS, OPT_DTLS1,
     OPT_DTLS1_2, OPT_TIMEOUT, OPT_MTU, OPT_LISTEN,
     OPT_ID_PREFIX, OPT_RAND, OPT_SERVERNAME, OPT_SERVERNAME_FATAL,
     OPT_CERT2, OPT_KEY2, OPT_NEXTPROTONEG, OPT_ALPN,
@@ -834,6 +834,9 @@
 #ifndef OPENSSL_NO_TLS1_2
     {"tls1_2", OPT_TLS1_2, '-', "just talk TLSv1.2"},
 #endif
+#ifndef OPENSSL_NO_TLS1_3
+    {"tls1_3", OPT_TLS1_3, '-', "just talk TLSv1.3"},
+#endif
 #ifndef OPENSSL_NO_DTLS
     {"dtls", OPT_DTLS, '-', "Use any DTLS version"},
     {"timeout", OPT_TIMEOUT, '-', "Enable timeouts"},
@@ -868,7 +871,7 @@
 
 #define IS_PROT_FLAG(o) \
  (o == OPT_SSL3 || o == OPT_TLS1 || o == OPT_TLS1_1 || o == OPT_TLS1_2 \
-  || o == OPT_DTLS || o == OPT_DTLS1 || o == OPT_DTLS1_2)
+  || o == OPT_TLS1_3 || o == OPT_DTLS || o == OPT_DTLS1 || o == OPT_DTLS1_2)
 
 int s_server_main(int argc, char *argv[])
 {
@@ -1321,6 +1324,10 @@
             min_version = SSL3_VERSION;
             max_version = SSL3_VERSION;
             break;
+        case OPT_TLS1_3:
+            min_version = TLS1_3_VERSION;
+            max_version = TLS1_3_VERSION;
+            break;
         case OPT_TLS1_2:
             min_version = TLS1_2_VERSION;
             max_version = TLS1_2_VERSION;