RG-2542 Backport the actual Table implementation to the RFC

[Aleksei Berezkin (aleksei-berezkin)]

Updates rfc/RG-2542-Reinvent-Table-Component.md to reflect the implementation as currently shipped in 8.0.0 (#9305), replacing the original design proposals with the actual API.

• TableProps, Column, SortOrder, and StandardRowRenderer (now DefaultItemRenderer) updated to match the actual types and signatures.
• All four examples updated to use the actual API (row clicks via onClick on DefaultItemRenderer, level prop instead of getItemLevel, etc).
• TableSelection (former Selection) noted as an optional standalone utility, not a Table prop.
• Third-party libraries: noted that TanStack Table and @dnd-kit were evaluated but not used.
• Branch/versioning section rewritten to reflect the actual branching strategy.
• Additionally, wrote a new example demonstrating a MobX-like optimization

[Copilot]

Pull request overview

Updates the RFC RG-2542-Reinvent-Table-Component.md to reflect the “as-shipped” Table API and usage patterns (as of Ring UI 8.0.0) rather than the original proposal, aligning the documented types, callbacks, and examples with the current component behavior.

Changes:

• Replaces the proposed TableProps / Column / sort types and row-renderer docs with the current API surface (e.g., SortOrder, DefaultItemRenderer).
• Updates all RFC examples to use the current rendering/click-handling approach via renderItem + DefaultItemRenderer.
• Refreshes RFC narrative sections (selection utility note, third-party library evaluation outcome, branching/versioning strategy).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.