Favorites: Favorites folders not saved on tvOS

Users reported that the favorites folders are not properly saved when the application is killed.

This might be linked to the location we save the favorites folders to as there is no persistent local storage on tvOS apart from the NSUserDefaults.

This issue can easily be reproduced on a physical AppleTV device.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information