Validation when moving items to incorrect folders

Context

Please see https://www.screencast.com/t/BiH50gXnz9 and the attached screenshot.

At the moment it is NOT possible to move a document into the images folder or any other non-documents folder (URL rewriter etc.). The documents >>>> other folder validation is there. If a user tries to take this action they are shown an error message as is shown in the screenshot. This is correct

However:

The non-document >>>> documents folder validation is missing (e.g. user tries to move an image or asset into the documents folder). They can do this and successfully move the item into the folder with no validation being displayed. This is incorrect

Acceptance Criteria

1. If a user tries to move an item from a non-document folder (such as anything in assets or images for example) into the documents folder they are shown a validation message reading 'The destination folder is not allowed to contain this type of item'.

1b. The message is styled, and functions, in the same way as the existing validation message for the document >>>> other folder action.

Notes

On code level, we may need to override DestinationDialog#checkFolderTypes and maybe DestinationDialog#checkPermissions() in DefaultWorkflowPlugin, like is done in DocumentWorkflowPlugin. Or do we need a new ImageWorkflowPlugin class?

Also it may need an addition to the org.hippoecm.repository.standardworkflow.FolderWorkflowImpl#hints in a separate REPO issue.