IntroPlugins are used to customize the intro dialog that prompts the user
for which config file and profile to use. Only one IntroPlugin can be
effectively used at a time; the program will use whichever one was loaded
Provide a list of paths to config files to include in the config file
dropdown menu. These will be provided in addition to any config files
the user has used in the past. This list may be null or empty.
List of config files to show to the user, or null.