Add support for `roots` and `root` in v48 editor for React integration

[Mati365]

📝 Provide a description of the new feature

Long story short:

ckeditor5-react/src/useMultiRootEditor.tsx

Line 156 in cc21103

rootsAttributes: attributes

rootsAttributes are no longer supported on V48. config.initialData will be also deprecated. We need to adjust our CKEditor component and useMultiRootEditor to make sure it'll work properly with V48 and map these properties to root / roots attributes.

Part of: ckeditor/ckeditor5#19885

[Mati365]

Format changed: ckeditor/ckeditor5#19885 (comment)