fix(menu): allow keyboard events to propogate from menu-items

packages/menu/src/Menu.ts

@@ -590,21 +590,27 @@ export class Menu extends SizedMixin(SpectrumElement, { noDefaultSize: true }) {
 
     protected navigateBetweenRelatedMenus(event: KeyboardEvent): void {
         const { key } = event;
-        event.stopPropagation();
+
+        if (key === 'ArrowRight' || key === 'ArrowLeft') {
+            event.preventDefault();
+        }
+
         const shouldOpenSubmenu =
             (this.isLTR && key === 'ArrowRight') ||
             (!this.isLTR && key === 'ArrowLeft');
         const shouldCloseSelfAsSubmenu =
             (this.isLTR && key === 'ArrowLeft') ||
             (!this.isLTR && key === 'ArrowRight');
         if (shouldOpenSubmenu) {
+            event.stopPropagation();
             const lastFocusedItem = this.childItems[this.focusedItemIndex];
             if (lastFocusedItem?.hasSubmenu) {
                 // Remove focus while opening overlay from keyboard or the visible focus
                 // will slip back to the first item in the menu.
                 lastFocusedItem.openOverlay();
             }
         } else if (shouldCloseSelfAsSubmenu && this.isSubmenu) {
+            event.stopPropagation();
             this.dispatchEvent(new Event('close', { bubbles: true }));
             this.updateSelectedItemIndex();
         }