Allow setting log-level for all nodes without needing to pass `ros_args`

[emersonknapp]

Description

Provide a way to change the log level for everything under launch (or under a given launch scope)

Motivation

Sometimes we want to set DEBUG level logging for everything, but this is not a Parameter, it's exposed via ros_arguments.

Design / Implementation Considerations

Node Action Extensions may provide the infrastructure needed to create this feature

Additional Information

No response