Expand access to SDK's struct bss_info (#8683)

The NONOS SDK's `struct bss_info` in `user_interface.h` has grown since the
beginning of this project. The additional elements are not accessible.
Add a method for R/O access to full `struct bss_info`.

See #7965 (comment)

libraries/ESP8266WiFi/src/ESP8266WiFiScan.cpp

@@ -147,6 +147,14 @@ void ESP8266WiFiScanClass::scanDelete() {
     _scanComplete = false;
 }
 
+/**
+ * returns const pointer to the requested scanned wifi entry for furthor parsing.
+ * @param networkItem int
+ * @return struct bss_info*, may be NULL
+ */
+const bss_info *ESP8266WiFiScanClass::getScanInfoByIndex(int i) {
+    return reinterpret_cast<const bss_info*>(_getScanInfoByIndex(i));
+};
 
 /**
  * loads all infos from a scanned wifi in to the ptr parameters

libraries/ESP8266WiFi/src/ESP8266WiFiScan.h

@@ -41,6 +41,7 @@ class ESP8266WiFiScanClass {
         void scanDelete();
 
         // scan result
+        const bss_info *getScanInfoByIndex(int i);
         bool getNetworkInfo(uint8_t networkItem, String &ssid, uint8_t &encryptionType, int32_t &RSSI, uint8_t* &BSSID, int32_t &channel, bool &isHidden);
 
         String SSID(uint8_t networkItem);