[APP-2375] Remove unused "Whats new" module

[rami-elementor]

✨ PR Description

Purpose: Remove "What's New" feature module from the application including UI components, API endpoints, and related hooks to streamline feature set and reduce codebase complexity.

Main changes:

• Removed WhatsNew module integration, API endpoint (getNotifications), and data hash comparison from settings pipeline
• Deleted WhatsNewDrawer component and associated menu button UI with notification indicator styling from My Account Menu
• Eliminated useWhatsNew hook dependency and whatsNewDataHash setting from plugin settings context and manager modules

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