docs: improve third-party component popup handling guidance and demos

[fangsmile]

Summary

This PR improves the documentation and demo code for handling third-party component popups (like Select, Cascader, etc.) within custom editors, addressing issues #4232 and #4213.

Changes:

1. Demo Updates (React & Vue):

   • Modified the Arco Select custom editor demos to use a stable CSS class (vtable-editor-select-popup) for the popup container.
   • Updated the isClickPopUp logic to check for this class, preventing the editor from exiting prematurely when interacting with popup elements (e.g., clicking a checkbox in a multi-select dropdown).

2. Guide Updates (Chinese & English):

   • Added a new section in the 'Custom Cell Editor' guide explaining how to handle popup DOM that is teleported to the body element.
   • Documented the recommended approach: configuring a stable class on the popup root and checking it in isEditorElement.
   • Provided specific configuration examples for both Arco Design (React/Vue) and Ant Design Select components.
   • Added a note about managing the execution order of onChange and endEdit to ensure the correct value is retrieved before the editor closes.

Impact:

These changes provide clear guidelines and working examples for users integrating complex third-party UI components into their custom table editors, ensuring a more stable and intuitive editing experience.