fix(ContextualMenu): restore onDismiss in Callout slot props

Destructuring onDismiss from userProps removed it from the ...rest spread
that gets passed to the Callout root slot. The Callout needs onDismiss to
function correctly — without it, the MenuButton SPACE key test consistently
failed because the menu couldn't dismiss/toggle properly.

Fix: destructure onDismiss AND explicitly pass it back in the root slot props.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Saadnajmi

packages/components/ContextualMenu/src/ContextualMenu.tsx

@@ -80,6 +80,7 @@ export const ContextualMenu = compose<ContextualMenuType>({
       root: {
         accessibilityRole: 'menu',
         setInitialFocus: shouldFocusOnMount,
+        onDismiss,
         ...rest,
       },
       container: {