fix: support checkbox state by record index

[fangsmile]

Summary

• Fix [Feature] ListTabe树形结构能不能提供清除某一个field的所有勾选状态的方法 #5211: add ListTable APIs setCellCheckboxStateByRecordIndex, clearCheckboxState, and clearAllCheckboxState.
• Support collapsed tree record paths such as [0, 1] without relying on visible row coordinates.
• Add dedicated demo: list/issue-5211-tree-checkbox-record-index.
• Add API docs and focused test coverage.

Validation

• BLOCKED: packages/vtable rushx compile and focused Jest are blocked by current develop vrender export/type issues, including runtime-installer, ILegacyBindingContext, ServiceIdentifier, and vrender-kits env/installers exports.
• BLOCKED: normal push hook is blocked by local Rush link state: Link flag invalid. Did you run rush install or rush update?

Fixes #5211