Persist DevIndex Animation Settings and Batch LocalStorage Reads

We want to persist the user's choices for the animation checkboxes in DevIndex so that users with low-end devices can permanently disable them.

To avoid sending multiple worker messages on startup, we will:

1. Enhance the Neo.main.addon.LocalStorage.readLocalStorageItem method to accept an array of strings for opts.key. If an array is provided, it will return an object containing all requested key-value pairs.
2. In DevIndex.view.ViewportController, update the startup logic to fetch ['devindexTheme', 'devindexSlowHeaderVisuals', 'devindexAnimateGridVisuals'] in a single call and apply them.
3. Update the DevIndex checkbox handlers to persist their state to localStorage when changed.