WiFiClientSecure: add loadCACert function (#3610)

Added loadCACert function

Author: rudivandrunen

libraries/ESP8266WiFi/src/WiFiClientSecure.h

@@ -67,6 +67,12 @@ class WiFiClientSecure : public WiFiClient {
   bool loadPrivateKey(TFile& file) {
     return loadPrivateKey(file, file.size());
   }
+  
+  template<typename TFile>
+  bool loadCACert(TFile& file) {
+    return loadCACert(file, file.size());
+  }
+
 
 protected:
     int _connectSSL(const char* hostName);