Additions to the Serial UART API (#22953)

- Added an empty constructor, setPort, and validatePort functions for Serial API
- Changed GPS to not allocate Serial object dynamically
- Moved access check on serial port name into the Serial API
- Improved the Qurt platform validatePort Serial function to implement a more rigorous check. Added safety check
to the setPort Serial function to make sure it isn't called after the port has been already opened.

platforms/qurt/include/SerialImpl.hpp

@@ -65,6 +65,7 @@ public:
 
 	const char *getPort() const;
 	bool setPort(const char *port);
+	static bool validatePort(const char *port);
 
 	uint32_t getBaudrate() const;
 	bool setBaudrate(uint32_t baudrate);