Support CKEditor 5

Complication: it looks like Emojione is now https://github.com/joypixels/emoji-toolkit , and there's no support for CKEditor 5 on their end, nor for Emoji Toolkit on CKEditor's end. However, there is a working library at https://github.com/linhx/ckeditor5-emoji . Perhaps that's what's intended for https://www.drupal.org/sandbox/sanduhrs/3274876 → .

The attached issue fork is crude and ugly, but it is functioning on my local environment, using the linhx/ckeditor5-emoji library. This is probably inappropriate for this module since this module explicitly is for the defunct emojione library. But this module is better supported than the alternatives, so I'm sharing this in hopes that it leads to something better!