components: add NodeWithMode class

[GuillaumeLaine]

Changes

• Adds template classes NodeWithMode and NodeWithModeExecutor to factorize repeated code in examples.
  • NodeWithMode<ModeT> instantiates and registers a mode of type ModeT.
  • NodeWithModeExecutor<ExecutorModeT, ModeT> instantiates and registers a mode executor of type ExecutorModeT. Also instantiates a mode of type ModeT, whose ownership is passed to the executor.
• Add doxygen group and subgroups for utils/ folder.
  • In Doxyfile, set EXTRACT_STATIC = YES because many utils functions are static qualified and weren't shown.

Example usage NodeWithMode:

class MyMode : public px4_ros2::ModeBase {...};
rclcpp::spin(std::make_shared<px4_ros2::NodeWithMode<MyMode>>("my_node"));

Example usage NodeWithModeExecutor:

class MyMode : public px4_ros2::ModeBase {...};
class MyExecutor : public px4_ros2::ModeExecutor {...};
rclcpp::spin(std::make_shared<px4_ros2::NodeWithMode<MyExecutor, MyMode>>("my_node"));

Discussion

Alternative name ideas for NodeWithMode?

• ModeControlNode
• ModeHandlingNode / ModeHandlerNode
• ...

JIRA: APX4-3823