Improve dialog framework

[t3chguy]

Better accessibility by returning focus, focus-trap including portals and more.
See ARIA examples for things to do

[daniellekirkwood]

@t3chguy would you update or close this issue? If it's still relevant it would benefit from a clearer description and then we can wrap it into our a11y work. In theory, it should be closed - we spent the last year working on Aria labels and focus.

[t3chguy]

Closing in favour of #22275