Fix disabled combobox items

[stephannLKN]

Fix disabled combobox item. ComboboxItem now checks if it contains disabled input to update its appearance.

ComboboxItem do
  ComboboxRadio(name: "fruit", disabled: true)
end

ComboboxItem do
  ComboboxCheckbox(name: "fruit", disabled: true)
end

[cirdes]

@stephannLKN , It would be great if aria-disabled also had this behavior.