refactor(EventEmitter): rename .next() to .emit()

BREAKING CHANGE:

EventEmitter#next(value) is deprecated, use EventEmitter#emit(value)
instead.

Closes #4287

Closes #5302

modules/playground/src/order_management/index.ts

@@ -147,7 +147,7 @@ class OrderItemComponent {
   @Input() item: OrderItem;
   @Output() delete = new EventEmitter();
 
-  onDelete(): void { this.delete.next(this.item); }
+  onDelete(): void { this.delete.emit(this.item); }
 }
 
 @Component({