esp_netif: Introduction of esp-netif component as a replacement of tcpip_adpter

- provides object oriented access to network intefaces
- not limited to default netifs
- more generic abstraction to network input output functions
- event handler registration removed from component responsibility
- backward compatibility layer for legacy tcpip_apapter APIs

Closes IDF-39

components/esp_wifi/src/wifi_init.c

@@ -19,6 +19,8 @@
 #include "esp_pm.h"
 #include "soc/rtc.h"
 #include "esp_wpa.h"
+#include "esp_netif.h"
+#include "tcpip_adapter_compatible/tcpip_adapter_compat.h"
 
 #if (CONFIG_ESP32_WIFI_RX_BA_WIN > CONFIG_ESP32_WIFI_DYNAMIC_RX_BUFFER_NUM)
 #error "WiFi configuration check: WARNING, WIFI_RX_BA_WIN should not be larger than WIFI_DYNAMIC_RX_BUFFER_NUM!"
@@ -124,10 +126,12 @@ esp_err_t esp_wifi_init(const wifi_init_config_t *config)
         }
     }
 #endif
+#if CONFIG_ESP_NETIF_USE_TCPIP_ADAPTER_COMPATIBLE_LAYER
     esp_err_t err = tcpip_adapter_set_default_wifi_handlers();
     if (err != ESP_OK) {
         ESP_LOGW(TAG, "Failed to set default Wi-Fi event handlers (0x%x)", err);
     }
+#endif
     esp_err_t result = esp_wifi_init_internal(config);
     if (result == ESP_OK) {
         esp_wifi_set_debug_log();