fix(material/menu): handle keyboard events through dispatcher

Currently `mat-menu` handles it keyboard events in the template, however this ignores the overlay's stacking context which can capture some events that it shouldn't.

These changes switch the menu to handling the events through the common dispatcher instead.

Fixes #29996.

Author: crisbeto

src/material/menu/menu-trigger.ts

@@ -412,11 +412,11 @@ export class MatMenuTrigger implements AfterContentInit, OnDestroy {
         config.positionStrategy as FlexibleConnectedPositionStrategy,
       );
       this._overlayRef = this._overlay.create(config);
-
-      // Consume the `keydownEvents` in order to prevent them from going to another overlay.
-      // Ideally we'd also have our keyboard event logic in here, however doing so will
-      // break anybody that may have implemented the `MatMenuPanel` themselves.
-      this._overlayRef.keydownEvents().subscribe();
+      this._overlayRef.keydownEvents().subscribe(event => {
+        if (this.menu instanceof MatMenu) {
+          this.menu._handleKeydown(event);
+        }
+      });
     }
 
     return this._overlayRef;

src/material/menu/menu.html

@@ -3,7 +3,6 @@
     class="mat-mdc-menu-panel"
     [id]="panelId"
     [class]="_classList"
-    (keydown)="_handleKeydown($event)"
     (click)="closed.emit('click')"
     [@transformMenu]="_panelAnimationState"
     (@transformMenu.start)="_onAnimationStart($event)"

src/material/menu/menu.spec.ts

@@ -473,16 +473,13 @@ describe('MatMenu', () => {
     fixture.componentInstance.trigger.openMenu();
 
     const panel = overlayContainerElement.querySelector('.mat-mdc-menu-panel')!;
-    const event = createKeyboardEvent('keydown', ESCAPE);
-    spyOn(event, 'stopPropagation').and.callThrough();
+    const event = dispatchKeyboardEvent(panel, 'keydown', ESCAPE);
 
-    dispatchEvent(panel, event);
     fixture.detectChanges();
     tick(500);
 
     expect(overlayContainerElement.textContent).toBe('');
     expect(event.defaultPrevented).toBe(true);
-    expect(event.stopPropagation).toHaveBeenCalled();
   }));
 
   it('should not close the menu when pressing ESCAPE with a modifier', fakeAsync(() => {

src/material/menu/menu.ts

@@ -385,10 +385,6 @@ export class MatMenu implements AfterContentInit, MatMenuPanel<MatMenuItem>, OnI
         manager.onKeydown(event);
         return;
     }
-
-    // Don't allow the event to propagate if we've already handled it, or it may
-    // end up reaching other overlays that were opened earlier (see #22694).
-    event.stopPropagation();
   }
 
   /**