Fix SortZone unit tests: Missing appName and Mock method

Problem

The unit tests for Neo.draggable.container.SortZone were failing due to two missing pieces of context:

1. Missing appName: The container created in the test did not define appName. This caused Neo.create to initialize the component without an associated app, leading to a crash in VdomLifecycle mixin when it tried to access app.vnodeInitialized.
2. Missing Mock Method: The component code calls Neo.main.addon.DragDrop.setDragProxyElement, but the test's mock for DragDrop did not define this method, causing a TypeError.

Solution

1. Update test/playwright/unit/draggable/container/SortZone.spec.mjs to pass appName when creating the test container.
2. Update the Neo.main.addon.DragDrop mock in test.beforeEach to include setDragProxyElement: () => Promise.resolve().

These changes ensure the test environment correctly simulates the runtime conditions required by SortZone.