payload_deliverer: Add gripper state output to "status" CLI output

- Previously it was hard to check which state the gripper was in
(GRAB/GRABBED/ etc), not even whether it was correctly initialized, this
commit adds that functionality

src/modules/payload_deliverer/payload_deliverer.h

@@ -77,6 +77,9 @@ public:
 	static int custom_command(int argc, char *argv[]);
 	static int print_usage(const char *reason = nullptr);
 
+	/** @see ModuleBase. Override "status" output when invoked via Commandline, to give detailed status **/
+	int print_status() override;
+
 	// Initializes the module
 	bool init();