Increase the maxlength of form input fields for custom class(es) and inline styles

Please find a patch which:
- Add maxlength 512 to classes, style and data-* fields
- Make ID, classes, style and data-* translatable (allowing english to be translatable on a site will allow to provide a different field label).
- Rework the validateForm to reduce code duplicate (use a foreach loop with ['block_attributes', 'block_title_attributes', 'block_content_attributes']).

The last submitted patch, 11: max_length_and_quick_fixes-3185302-11.patch, failed testing. View results →

Please find a new patch.
I fixed a typo (I think?) in a message which is tested in unit test. I fixed the typo in the tests as well.
I also fixed the coding standard error.

@vbouchet - Thanks for your work on this issue. Let's rescope the patch to only change the character limit. I agree with the other changes, but let's open follow-up issues for those - one for the translatable titles and another for reduce code duplication.

Please find the patch for max-length only. I will raise independent tickets for the other points.

Automatically closed - issue fixed for 2 weeks with no activity.