add cases to test session resumption with different ticket_flags

This commit add test cases to test if the check of kex change mode
in SessionTicket works well.

Signed-off-by: Pengyu Lv <pengyu.lv@arm.com>
diff --git a/programs/ssl/ssl_client2.c b/programs/ssl/ssl_client2.c
index 4b3799f..d64675d 100644
--- a/programs/ssl/ssl_client2.c
+++ b/programs/ssl/ssl_client2.c
@@ -1215,6 +1215,9 @@
                 opt.tls13_kex_modes = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL;
             } else if (strcmp(q, "all") == 0) {
                 opt.tls13_kex_modes = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_ALL;
+            } else if (strcmp(q, "psk_or_ephemeral") == 0) {
+                opt.tls13_kex_modes = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK |
+                                      MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL;
             } else {
                 goto usage;
             }