Add deprecated attribute to setThingId() function

Author: pennam

src/ArduinoIoTCloud.h

@@ -91,7 +91,7 @@ class ArduinoIoTCloudClass
             void push();
             bool setTimestamp(String const & prop_name, unsigned long const timestamp);
 
-    inline void     setThingId (String const thing_id)  { _thing_id = thing_id; };
+    inline void     setThingId (String const thing_id)  { _thing_id = thing_id; }; __attribute__((deprecated("It is no longer necessary to configure a THING ID.")));
     inline String & getThingId ()                       { return _thing_id; };
     inline void     setDeviceId(String const device_id) { _device_id = device_id; };
     inline String & getDeviceId()                       { return _device_id; };