[ET-VK] Wire the missing resize functions for embedding and index_select

[msluszniak]

Summary

add_embedding_legacy_node() and both index_select node builders pass nullptr as their resizing logic:

      // Resize Args
      {},
      // Resizing Logic
      nullptr));

even though resize_embedding_node, resize_index_select_channel_node and the local resize_fn are already defined immediately above them and do the right thing. Under dynamic shapes the outputs keep the extents they were built with (the upper bound) instead of tracking the real input sizes, so consumers read them at the wrong size.

register_index_select() also does not set supports_resize, so this patch sets it now that the op honours resize.

Fix

Pass the resize functions that already exist. Three one-line changes plus the registry flag.

How it surfaced

A TTS model on Adreno 840 produced wrong outputs after an unrelated change moved a partition boundary. The embedding output had been keeping its upper-bound extents all along; previously a CPU round-trip happened to re-establish the correct shape downstream, so the defect was masked. Once the gather stayed on the GPU the stale extents reached the consumer.

Verified on a Galaxy S26 Ultra: with these wired up, the affected sub-models return correct shapes and match their CPU references (cosine >= 0.999 at sequence lengths well below the dynamic bound) where before they were wrong at every length except the bound itself.

Note this class of bug is hard to see with executor_runner, which can only run at the dynamic upper bound -- exactly the one shape where a missing resize is harmless.

[pytorch-bot]

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