[AriaNotify] Braille Support

[alisonmaher]

As discussed in #1958 (comment), there may be cases where an author would want to provide a separate notification string for braille users. @cookiecrook noted that if so, it should align with aria-braille* attributes.

I think this is a great idea, and I could imagine use cases where an author would want to provide different strings for braille. However, I would like to propose that we consider this for a future version of the API instead to allow us to gather feedback from developers and end users as ariaNotify starts to get adopted with its current set of functionality. This will help inform the best way to incorporate this additional customizability going forward.

[alisonmaher]

This was discussed at TPAC:

keithamus: there are a couple open issues I can lump together that I think we can defer. But I think braille support and speech markup we can design around those later

The group seemed to agree with deferring this till a future version

[keithamus]

I think we've successfully captured a resolution around this, which is that we should defer support for these until a future version.

I'll close this for now but I think we can revisit it once we know more about how this API is used once it ships!