Upgrade from CKEditor 4 to CKEditor 5

[sandbergja]

• [x] Follow the upgrade steps from Drupal documentation
• [x] Turn off the CKEditor 4 module and turn on the CKEditor 5 module in the UI locally.
• [x] Remove ckeditor-related entries in composer.json
• [x] Test locally to make sure the site is still working as expected
• [x] Deploy your branch to staging
• [x] Deploy your branch to prod