Remove the DndResources class and have users of this class create a CustomSongResources directly. #634
Description
The original implementation of DndResources class has been extracted
into a CustomSongResources superclass in commit cc6a6e7,
so that part of its logic can be re-used in other contexts, such as in commit ba9e15b.
Now this DndResources class is really dumb and we want to prefer composition over inheritance.
This class should be removed.
This issue has been automatically created by todo-actions based on a TODO comment found in src/resources/dnd-resources.ts:8. It will automatically be closed when the TODO comment is removed from the default branch (master).