Fix external web server launcher war output path configuration

Fix the war output path chooser in the external web server launcher configurator.
- The input needs better description.
- The war output path chooser needs a file chooser.
- The input needs to then be set as the proper argument.
- Add more help describing what it is.

Locate the external web server launcher configurator and inspect the existing WAR output path input, chooser, and launcher argument wiring. Done means the input is clearly described, uses a file chooser, supplies the correct argument, and includes help text explaining the setting.

索引モデルが issue の本文から書いたものです。