[New Rich Text Editor]: improve performance by lazy loading heavy extensions

[habibayman]

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Desired behavior

Implement code splitting for resource-heavy extensions such as MathLive and Code Block syntax highlighting (e.g., lowlight, highlight.js and related dependencies).
The goal is to defer loading these extensions until they are actually used, in order to reduce initial bundle size and improve editor performance — especially for users who don’t immediately need these features.

I plan to begin with lazy-loading the Math and CodeBlock-related extensions and will also explore additional opportunities for optimization within those implementations.

Current behavior

• Component is available for isolated development at http://localhost:8080/editor-dev#/
• All the buttons in the toolbar are fully functioning
• All extensions (including heavy ones) are loaded upfront

Notes:

• Most of the heavy extensions were introduced in PR feat(texteditor): implement insertion toolbar actions #5155
• They are working correctly, but performance can be improved
• This task focuses on making those enhancements through lazy loading and code-splitting

Labels

• DEV: frontend