Create load_parameters and delete_parameters methods on rclcpp::[A]syncParametersClient

[BriceRenaudeau]

Feature request

Feature description

It would be great to add these two methods to rclcpp::[A]syncParametersClient:

1. load_parameters to do the same as ros2 param load [node] [yaml_file]
2. delete_parameters to do the same as ros2 param delete [node] [parameters]

Implementation considerations

Right now, I am using a system call to execute these two commands.

[BriceRenaudeau]

To delete a parameter one can use :

// without value, it sets the parameter to NOT_SET, behave like delete
auto set_results = parameter_client->set_parameters({rclcpp::Parameter(param)});

[wjwwood]

Makes sense to me, we only have them implemented in rclpy (or maybe just in ros2param). Bonus points for considering if working it into rcl so rclpy and rclcpp can share the same implementation of these two functions makes sense.

[BriceRenaudeau]

Linked issue #1029

[sloretz]

Closing as this appears to have been resolved by #1596