Accessibility: Adds aria tags to VizTooltip so screen readers announce them (#68247)

packages/grafana-ui/src/components/VizTooltip/VizTooltipContainer.tsx

@@ -100,6 +100,8 @@ export const VizTooltipContainer = ({
         transform: `translate(${placement.x}px, ${placement.y}px)`,
         transition: 'transform ease-out 0.1s',
       }}
+      aria-live="polite"
+      aria-atomic="true"
       {...otherProps}
       className={cx(styles.wrapper, className)}
     >