examples: added ESP-NETIF L2 TAP example

* Original commit: espressif/esp-idf@fcdb0306d0

examples/common_components/protocol_examples_common/connect.c

@@ -479,6 +479,7 @@ static void eth_stop(void)
     ESP_ERROR_CHECK(esp_eth_stop(s_eth_handle));
     ESP_ERROR_CHECK(esp_eth_del_netif_glue(s_eth_glue));
     ESP_ERROR_CHECK(esp_eth_driver_uninstall(s_eth_handle));
+    s_eth_handle = NULL;
     ESP_ERROR_CHECK(s_phy->del(s_phy));
     ESP_ERROR_CHECK(s_mac->del(s_mac));
 
@@ -486,6 +487,11 @@ static void eth_stop(void)
     s_example_esp_netif = NULL;
 }
 
+esp_eth_handle_t get_example_eth_handle(void)
+{
+    return s_eth_handle;
+}
+
 #endif // CONFIG_EXAMPLE_CONNECT_ETHERNET
 
 esp_netif_t *get_example_netif(void)