Modify esp-tls and tcp_transport to support keep alive for tcp and ssl connection

Closes IDFGH-4543

components/tcp_transport/include/esp_transport_tcp.h

@@ -21,6 +21,15 @@
 extern "C" {
 #endif
 
+/**
+ * @brief      Set TCP keep-alive configuration
+ *
+ * @param[in]  t               The transport handle
+ * @param[in]  keep_alive_cfg  The keep-alive config
+ *
+ */
+void esp_transport_tcp_set_keep_alive(esp_transport_handle_t t, esp_transport_keep_alive_t *keep_alive_cfg);
+
 /**
  * @brief      Create TCP transport, the transport handle must be release esp_transport_destroy callback
  *