[ET-VK][ops] Add buffer unfold support

Implement `aten.unfold_copy.default` for Vulkan buffer tensors, including high-rank indexing and dynamic resize support. Add focused coverage for general, high-rank, and SceneX audio shapes. Authored with Codex.

Differential Revision: [D114382687](https://our.internmc.facebook.com/intern/diff/D114382687/)


ghstack-source-id: 409188517
Pull-Request: https://github.com/pytorch/executorch/pull/21521