EAP-TLS server: Add application data to indicate end of v1.3 handshake

EAP-TLS server: Add application data to indicate end of v1.3 handshake

This adds an encrypted version of a one octet application data payload
to the end of the handshake when TLS v1.3 is used to indicate explicit
termination of the handshake (either after Finished message or after the
optional NewSessionTicket message). The current
draft-ietf-emu-eap-tls13-05 defines this to be a zero length payload,
but since that is not allowed by OpenSSL, use a one octet payload
instead for now with hopes of getting the draft specification updated
instead of having to modify OpenSSL for this.

Signed-off-by: Jouni Malinen <j@w1.fi>