Reduce nesting for form validation
Reduce nesting for form validation

- Move .error-message out from the parent .error, so we don’t need a
parent class to apply an .error-message style (bold 19px red text).
- Ungroup .error and .error-summary as error-summary already sets the
borders and padding it needs
- Fix typo

alphagov/govuk_elements,alphagov/govuk_elements,alphagov/govuk_elements,alphagov/govuk_elements