Update state machine to be closer to TLS1.3

This is a major overhaul of the TLSv1.3 state machine. Currently it still
looks like TLSv1.2. This commit changes things around so that it starts
to look a bit less like TLSv1.2 and bit more like TLSv1.3.

After this commit we have:

ClientHello
+ key_share          ---->
                           ServerHello
                           +key_share
                           {CertificateRequest*}
                           {Certificate*}
                           {CertificateStatus*}
                     <---- {Finished}
{Certificate*}
{CertificateVerify*}
{Finished}           ---->
[ApplicationData]    <---> [Application Data]

Key differences between this intermediate position and the final TLSv1.3
position are:
- No EncryptedExtensions message yet
- No server side CertificateVerify message yet
- CertificateStatus still exists as a separate message
- A number of the messages are still in the TLSv1.2 format
- Still running on the TLSv1.2 record layer

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

ssl/ssl_err.c

diff --git a/ssl/ssl_err.c b/ssl/ssl_err.c
index b7ba8a5..825c563 100644
--- a/ssl/ssl_err.c
+++ b/ssl/ssl_err.c
@@ -239,6 +239,7 @@
     {ERR_FUNC(SSL_F_STATE_MACHINE), "state_machine"},
     {ERR_FUNC(SSL_F_TLS12_CHECK_PEER_SIGALG), "tls12_check_peer_sigalg"},
     {ERR_FUNC(SSL_F_TLS13_CHANGE_CIPHER_STATE), "tls13_change_cipher_state"},
+    {ERR_FUNC(SSL_F_TLS13_SETUP_KEY_BLOCK), "tls13_setup_key_block"},
     {ERR_FUNC(SSL_F_TLS1_CHANGE_CIPHER_STATE), "tls1_change_cipher_state"},
     {ERR_FUNC(SSL_F_TLS1_CHECK_DUPLICATE_EXTENSIONS),
      "tls1_check_duplicate_extensions"},
@@ -368,6 +369,7 @@
     {ERR_REASON(SSL_R_BLOCK_CIPHER_PAD_IS_WRONG),
      "block cipher pad is wrong"},
     {ERR_REASON(SSL_R_BN_LIB), "bn lib"},
+    {ERR_REASON(SSL_R_CANNOT_CHANGE_CIPHER), "cannot change cipher"},
     {ERR_REASON(SSL_R_CA_DN_LENGTH_MISMATCH), "ca dn length mismatch"},
     {ERR_REASON(SSL_R_CA_KEY_TOO_SMALL), "ca key too small"},
     {ERR_REASON(SSL_R_CA_MD_TOO_WEAK), "ca md too weak"},