[Accessibility] Improve rewriting aria attributes (`ObserveAttributesMixin` mixin) to the target element

[anna-lach]

• Improve ObserveAttributesMixin to make it working with observedAttributes getter in the mixin, not in the component. Check if it's not breaking any current behaviour and it's working fine with other attributes like e.g. in the sl-menu-button with fill attribute, that should be applied to sl-menu-button and sl-button.
• Update all components that already use ObserveAttributesMixin.