Issue #3263384 by nod_, Wim Leers: Add ckeditor5-code-block package and CodeBlock plugin

core/assets/vendor/ckeditor5/code-block/code-block.js

core/assets/vendor/ckeditor5/code-block/translations/az.js

core/assets/vendor/ckeditor5/code-block/translations/bs.js

core/assets/vendor/ckeditor5/code-block/translations/cs.js

core/assets/vendor/ckeditor5/code-block/translations/da.js

.../assets/vendor/ckeditor5/code-block/translations/de-ch.js

core/assets/vendor/ckeditor5/code-block/translations/de.js

core/assets/vendor/ckeditor5/code-block/translations/el.js

.../assets/vendor/ckeditor5/code-block/translations/en-au.js

core/assets/vendor/ckeditor5/code-block/translations/es.js

core/assets/vendor/ckeditor5/code-block/translations/et.js

core/assets/vendor/ckeditor5/code-block/translations/fa.js

core/assets/vendor/ckeditor5/code-block/translations/fr.js

core/assets/vendor/ckeditor5/code-block/translations/gl.js

core/assets/vendor/ckeditor5/code-block/translations/hi.js

core/assets/vendor/ckeditor5/code-block/translations/hr.js

core/assets/vendor/ckeditor5/code-block/translations/hu.js

core/assets/vendor/ckeditor5/code-block/translations/id.js

core/assets/vendor/ckeditor5/code-block/translations/it.js

core/assets/vendor/ckeditor5/code-block/translations/ja.js