cannot configure optional argument after fzf-based interactive selection

@tonynajjar

i do not think this is issue, should be more like discussion. this just came up in ROS Japan Developer Meeting.
looks like this is constrain compared to tab completion.

$ ros2 topic echo <enter>

goes in interactive selection mode, and once we pick the topic, it will execute the command right away.
but it is likely that user wants to add the command line argument after the select.

such as,

$ ros2 topic echo /rosout --use-sim-time --clear ...

if we want to add any optional arguments with interactive selection mode, we need to make sure all the optional arguments set before .

nice to have here is that, interactive selection mode just place the selected <topic name> in the command line, and lets the user to continue to assign the optional argument. and finally user is responsible to execute the command?