[ET-VK] Add Vulkan ops for skin segmentation and EdgeTAM models

[SS-JIA]

Stack from ghstack (oldest at bottom):

• [ET-VK] Add aten.index.Tensor op and tests #17710
• -> [ET-VK] Add Vulkan ops for skin segmentation and EdgeTAM models #17709
• [ET-VK][q8_ops] Add int8x4_buffer_to_nchw shader and refactor Int8x4Staging #17708
• [ET-VK][ez] Fix global workgroup size underflow for sub-4D tensors in block config dispatch #17707

Implement several missing Vulkan operators needed to reduce graph
fragmentation in the skin segmentation and EdgeTAM models.

Skin segmentation ops:

• aten.where.self: already had C++ and GLSL implementations but was
  missing the Python partitioner registration.
• aten.bitwise_and.Tensor: added as a new binary_op shader variant
  operating on uint8 (bool) tensors.

EdgeTAM partitioning fixes:

• Comparison ops (eq, lt, le, gt, ge): were registered under the
  generic BinaryOp features which inherited FP_INT_T as the output
  dtype set. The partitioner correctly rejected these because their
  outputs are bool tensors. Split them into a dedicated
  register_comparison_ops registration with outputs_dtypes=BOOL_T. The
  binary_op.glsl shader already handles bool output via the
  IS_COMPARISON_OP path (uint8 storage), so no shader changes are
  needed.
• aten.copy.default: not in the op registry, causing a subgraph break
  in the first-frame model. This op appears when valid_num_points.to()
  is called with matching dtype (a no-op cast). Add it to
  RemoveRedundantOpsTransform so it is eliminated before the partitioner
  runs. Also register it as an ephemeral op as a fallback. The removal
  logic requires a _src_arg1_ops set to handle the copy.default(self,
  src) argument order, where the replacement target is args[1] (src)
  rather than args[0] (self) as in all other redundant ops.

Differential Revision: D94364641

cc @manuelcandales @digantdesai @cbilgin

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/17709

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❌ 3 New Failures

As of commit 88544f6 with merge base 63f9724 ():

NEW FAILURES - The following jobs have failed:

• pull / unittest-arm-backend-with-no-deps (test_pytest_ops_tosa) / linux-job (gh)
  RuntimeError: Command docker exec -t bfbe4f28a4ff9cf7c34c379a3c9602b527a6630b6d8601b088ed24fb47a90901 /exec failed with exit code 1
• Test CUDA Builds / test-model-cuda-e2e (mistralai, Voxtral-Mini-3B-2507, quantized-int4-tile-packed) / linux-job (gh)
  RuntimeError: Command docker exec -t 2bd6fd713cdb5f9421dbb6c6004f064fe12acb71dddd8829ba9264294445f551 /exec failed with exit code 55
• Test CUDA Builds / test-model-cuda-e2e (mistralai, Voxtral-Mini-3B-2507, quantized-int4-weight-only) / linux-job (gh)
  RuntimeError: Command docker exec -t bf963c49a054550e876664ad81b7848f37b5df6e7dacd05142795a238d096646 /exec failed with exit code 55

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