Add an option for messages to be set as status

Sometimes, the message boxes such as `success`, `warning` and `error` get used through the UI to indicate the status of a process. All of these boxes should be treated specially by screen readers.

The standard way to ask for this is to add the role=status or the aria properties aria-live or aria-atomic.

Note that this should be toggled off by default, we don't want all the warning box to be displayed as status of a current process. Sometimes they just provide extra context on a piece of info and do not need to get a special focus.
E.g., a documentation page with 20 warning boxes in different places, they might be important to highlight the importance of some info, but the user doesn't need a list of them when opening the page.

This was first reported by Zendis in their accessibility audit of XWiki.