[REF] web: field decoration

This commit refactors the way the decoration-xxx attributes are
applied to field widgets/components, in a way that it can be
overridden in a given field or component to generate the approriate
className. By default, 'decoration-x' applies className 'text-x'.

This will be necessary for the new 'FieldBadge' component, which
needs to apply 'bg-x' classNames instead of 'text-x'.

Part of task 2195254