Extract utils from LocalStorageSync component

What does this MR do and why?

This change extracts localStorage handling logic from the local_storage_sync.vue component into a dedicated utility module.

The new local_storage.js utility provides three main functions: getStorageValue, saveStorageValue, and removeStorageValue, which handle serialization, deserialization, and error handling when working with browser localStorage.

The component now uses these utility functions instead of implementing its own methods.

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