Don't automatically hide launcher

Rather than auto-hiding the launcher once an engine is selected, prompt the user to hide it if `$HIDE_LAUNCHER` doesn't exist, e.g.:

```bash
zenity --question \
--title="Launcher Option" \
--text="Do you want to hide the launcher next time?" \
--ok-label="Yes" \
--cancel-label="No"

if [[ $? -eq 0 ]]; then
touch "${HIDE_LAUNCHER}"
fi
```