The main PlatformDirs resource. Can be fetched with Res in a system or
world.resource::<PlatformDirs>(). There are no mutable methods on PlatformDirs,
so there is no point fetching it mutably.
Add this plugin to your Bevy App to make the PlatformDirs Resource available.
When created by default this will provide the default system paths. If
created with new and a name, this will provide customized paths.