examples: Add common linux component tapif_io

That can be used with linux target on lwip to pass packets from lwip to
linux host networking stack, e.g. routing the trafic to internet.

examples/common_components/protocol_examples_tapif_io/linux_connect.c

@@ -0,0 +1,51 @@
+/*
+ * SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include "esp_err.h"
+#include "esp_netif.h"      // esp-netif
+#include "tapio.h"          // esp-netif's driver side
+#include "lwip/tapif.h"     // esp-netif's network stack side
+
+esp_err_t example_connect(void)
+{
+#if CONFIG_EXAMPLE_CONNECT_LWIP_TAPIF
+    // configure linux tapio
+    esp_netif_driver_ifconfig_t driver_cfg = {
+            .handle = tapio_create(),
+            .transmit = tapio_output,
+    };
+    // configure lwip netif for the tapif
+    struct esp_netif_netstack_config stack_cfg = {
+            .lwip = {
+                    .init_fn = lwip_tapif_init,
+                    .input_fn = lwip_tapif_input,
+            }
+    };
+    // configure inherent esp-netif parameters
+    esp_netif_ip_info_t ip_info = {};
+    ip_info.ip.addr = ipaddr_addr(CONFIG_EXAMPLE_CONNECT_TAPIF_IP_ADDR);
+    ip_info.netmask.addr = ipaddr_addr(CONFIG_EXAMPLE_CONNECT_TAPIF_NETMASK);
+    ip_info.gw.addr = ipaddr_addr(CONFIG_EXAMPLE_CONNECT_TAPIF_GW);
+
+    esp_netif_inherent_config_t base_cfg = {
+            .if_key = "TAP",
+            .flags = ESP_NETIF_FLAG_AUTOUP,
+            .ip_info = &ip_info,
+            .route_prio = 100
+    };
+
+    // put all configs together
+    esp_netif_config_t cfg = {
+            .base = &base_cfg,
+            .driver = &driver_cfg,
+            .stack = &stack_cfg
+    };
+
+    // create the interface and attach it to the tapio-handle
+    esp_netif_t *tap_netif = esp_netif_new(&cfg);
+    esp_netif_attach(tap_netif, driver_cfg.handle);
+#endif // EXAMPLE_CONNECT_LWIP_TAPIF
+    return ESP_OK;
+}