a11y: feedback buttons do not expose their submitted state

ActionBarPrimitive.FeedbackPositive and ActionBarPrimitive.FeedbackNegative mark a submitted rating with data-submitted="true" only (packages/react/src/primitives/actionBar/ActionBarFeedbackPositive.tsx, same in the negative one). templates style that attribute with a background, so the selected rating is visible but a screen reader cannot tell which of Helpful or Not helpful is active.

the state belongs to the primitives, so the fix is there rather than in each template: set aria-pressed from the same isSubmitted selector, next to data-submitted. that covers the default thread (which shows both buttons since #7709), the docs examples and every custom action bar.

came up in review on #7709 and was left out of that PR because it changes the DOM of every consumer.