Implement a settings file

[Léane GRASSER]

Implementing settings will allow us to customize team names and window resolution among other webapp or Java backend settings.

Using JSON looks like the easiest method to implement it, as we already have Moshi in our dependencies and it's the easiest way to make settings. A GUI might be interesting as well, with a way to update settings on the fly (our current messages should be sufficient already for this task).