This is an extension method to help a user in processing a DragEventArgs to a object type of their choice.
- Take a function to create the required Type from a FileStream.
- Take an Action to handle an exception.
- Check that the drop array contains a FileDrop.
- Select the First FileInfo and open a FileStream.
- Execute createAction with this FileStream. If this fails the exception will be handled by the onFailed callback.