Simulator GUI: Display echo text rather than action name

As a user of the simulator GUI I would like to see the echo "text" rather than the action name "echo" when viewing the simulator actions on the activity page so that the scenario can output important information or dynamic information to the user during scenario execution

Start by locating the simulator GUI activity page that renders simulator actions, then trace how the echo action is displayed. The change is complete when the page shows the echo text rather than the action name "echo" during scenario execution.

Written by the indexing model from the issue text.