Port CRSF RC driver to new Serial UART API (#22917)

* Added implementations of Rx Tx swap and single wire for new UART API needed by CRSF driver
* Added inverted mode to Serial interface API

platforms/common/include/px4_platform_common/Serial.hpp

@@ -65,6 +65,8 @@ public:
 
 	ssize_t write(const void *buffer, size_t buffer_size);
 
+	void flush();
+
 	// If port is already open then the following configuration functions
 	// will reconfigure the port. If the port is not yet open then they will
 	// simply store the configuration in preparation for the port to be opened.
@@ -84,6 +86,15 @@ public:
 	FlowControl getFlowcontrol() const;
 	bool setFlowcontrol(FlowControl flowcontrol);
 
+	bool getSingleWireMode() const;
+	bool setSingleWireMode();
+
+	bool getSwapRxTxMode() const;
+	bool setSwapRxTxMode();
+
+	bool getInvertedMode() const;
+	bool setInvertedMode(bool enable);
+
 	static bool validatePort(const char *port);
 	bool setPort(const char *port);
 	const char *getPort() const;