This change is intended to be backwards-compatible with all the previous arguments to `DButton`.
A deprecation warning will be triggered when a string is passed to the `@action` argument. This kind of action bubbling has been deprecated in Ember for some time, and should be updated to use closure actions.
Co-authored-by: Dan Gebhardt <dan@cerebris.com>
Co-authored-by: David Taylor <david@taylorhq.com>