Consider providing user control of log file base names

[sea-bass]

Feature request

Feature description

I have reported an issue in the ros2cli repo recently (ros2/ros2cli#856) which hopefully will gain traction.

The general idea in the above issue -- and please read that for more details -- is that the default log file names right now are prepended with the executable name (in the C++ case) or the Python executable name (e.g., python3) in the Python case.

The investigation is leading to maybe providing a user-configurable parameter for ros2 run that allows the user to provide their own base name for log files.

Per @fujitatomoya's suggestion, I wanted to open this up here as well to ensure that the launch_ros tools track the above issue and have a way to expose this through ros2 launch, and the launch APIs, as well.