ESP8266WiFiMulti - get number of APs in the list (#9082)

When having some more complex setups it might be helpful to know the number of APs already added to the list.

libraries/ESP8266WiFi/src/ESP8266WiFiMulti.h

@@ -69,7 +69,7 @@ class ESP8266WiFiMulti
     wl_status_t run(uint32_t connectTimeoutMs=WIFI_CONNECT_TIMEOUT_MS);
 
     void cleanAPlist();
-
+    int count() { return _APlist.size(); }
 private:
     WifiAPlist _APlist;
     bool _firstRun;