ariaLiveMessages/LiveRegion could operate on JSX rather on strings

[PinkaminaDianePie]

I need to pass a string with some markup to ariaLiveMessages prop, so the content of ariaLiveRegion will be something like Option <span lang="fr">Français</span> selected. Currently, ariaLiveMessages and LiveRegion operate on the concatenation of strings instead, so I have Option [object Object] selected. If all logic would be based on JSX, it would be easier to provide internationalization support for react-select.