Make Soft AP build against Arduino SDK 3.0.0

It seems that the global dhcpSoftAP is used to encapsulate some of the
DHCP functionality. Make use of the new API.

See upstream change:
esp8266/Arduino#6680

Author: agners

esphome/components/wifi/wifi_component_esp8266.cpp

@@ -10,6 +10,10 @@
 #include <wpa2_enterprise.h>
 #endif
 
+#ifdef WIFI_IS_OFF_AT_BOOT // Identifies ESP8266 Arduino 3.0.0
+#define ARDUINO_ESP8266_RELEASE_3
+#endif
+
 extern "C" {
 #include "lwip/err.h"
 #include "lwip/dns.h"
@@ -18,8 +22,15 @@ extern "C" {
 #if LWIP_IPV6
 #include "lwip/netif.h"  // struct netif
 #endif
+#ifdef ARDUINO_ESP8266_RELEASE_3
+#include "LwipDhcpServer.h"
+#define wifi_softap_set_dhcps_lease(lease) dhcpSoftAP.set_dhcps_lease(lease)
+#define wifi_softap_set_dhcps_lease_time(time) dhcpSoftAP.set_dhcps_lease_time(time)
+#define wifi_softap_set_dhcps_offer_option(offer, mode) dhcpSoftAP.set_dhcps_offer_option(offer, mode)
+#endif
 }
 
+
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 #include "esphome/core/esphal.h"
@@ -649,6 +660,10 @@ bool WiFiComponent::wifi_ap_ip_config_(optional<ManualIP> manual_ip) {
     return false;
   }
 
+#ifdef ARDUINO_ESP8266_RELEASE_3
+  dhcpSoftAP.begin(&info);
+#endif
+
   struct dhcps_lease lease {};
   IPAddress start_address = info.ip.addr;
   start_address[3] += 99;