Feature request

Feature description

Most of the times when a developer wants to do debugging, one of the first things they do is to turn on debug logging. One way to do that in ros2 is to run a command and increase the logging level, something like:

ros2 run demo_nodes_cpp talker --ros-args --log-level DEBUG

The problem with this is that it enables debugging on all components, not just the node. While that may be what the user wants, in general I think they typically just want to debug their own node to start with. We should provide a generic way to change the log level of a particular node, not of everything.

Implementation considerations

There's some possibility that this already exists in the ROS 2 ecosystem. If it does, I don't think it is documented anywhere. So either we need to implement this and document it, or something needs to show me how to currently do it so I can document it.