Switch to CKEditor 4

[juleskuehn]

Using CKEditor 5 has caused a number of issues:

• Language of French content within rich text editors is tagged as English (despite setting CKEditor 5 content language to French).
• Alphabetical list styles are not visible in the rich text editor, though present in the HTML of the clauses (which was generated outside of CKEditor).
• CKEditor 5 is incompatible with Internet Explorer 11. Content remains editable as raw HTML in IE11.
• CKEditor 5 has keyboard accessibility issues when working with tables and images.

I suggest switching to CKEditor 4 and using the Language and List-styles plugins. RTE initialization code in /public/ally-req.js will need to be updated along with the CKEditor build at /public/ckeditor.js.

(Before switching to CKEditor 4, we should check if the issues have been resolved in a newer release of CKEditor 5.)