All errors should have role alert for better accessibility when using client side validation

Working on it!!

The patch successfully applied for me the changes looks good to me because it adds accessibility to errors.

I've tested it on macOS with VoiceOver. I tried to save a webform without filling in the required fields. The screen reader announced the error message of the latest required field.

I think it's correct. But maybe it would be a good idea to have an a11y expert test the solution as well.