Features
   * Mbed TLS supports TLS 1.3 key establishment via pre-shared keys,
     pre-shared keys provisioned externally or via the ticket mechanism
     (session resumption).
     The MBEDTLS_SSL_SESSION_TICKETS configuration option controls the support
     for the ticket mechanism.
     MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_xxx_ENABLED configuration options
     have been introduced to control the support for the three possible
     TLS 1.3 key exchange modes.