[ET-VK][qlinear] Look through output view_copy when detecting output quantization

[SS-JIA]

Stack from ghstack (oldest at bottom):

• [ET-VK][qlinear] Add bmm support to quantized linear pattern detector #18017
• [ET-VK][qconv] Add q8ta_conv2d_transposed operator #18016
• [ET-VK][qdq] Support high-dimensional tensors in quantize/dequantize per tensor #18015
• -> [ET-VK][qlinear] Look through output view_copy when detecting output quantization #18014
• [ET-VK][ez] Fix duplicate placeholder target in create_constant_placeholder #18013

When aten.linear has 3D+ inputs, it decomposes into
view_copy -> mm -> view_copy. The output view_copy between mm and the
subsequent quantize_per_tensor node was preventing the pattern matcher
from detecting output quantization, causing the match to fall through
to linear_q8ta_q8csw instead of q8ta_linear_gemv. This caused a
dtype mismatch during FakeTensor re-tracing in FusePatternsPass because
linear_q8ta_q8csw's composite implementation does not dequantize its
input, producing int8 output where float32 was expected.

Mirror the existing input-side view_copy handling (lines 99-104) on the
output side so the quantize node is found through the view_copy.

Differential Revision: D95807075

cc @manuelcandales @digantdesai @cbilgin

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❌ 5 New Failures, 1 Cancelled Job

As of commit d7eda9c with merge base f09bd55 ():

NEW FAILURES - The following jobs have failed:

• pull / unittest-arm-backend-with-no-deps (test_pytest_models_tosa) / linux-job (gh)
  RuntimeError: Command docker exec -t 7c5eb6e1f76841d365a0b5948a88f492f6ce7aeca8e418feb381ee5944d9e86e /exec failed with exit code 1
• pull / unittest-editable / macos / macos-job (gh)
  export/tests/test_target_recipes.py::TestTargetRecipes::test_mv3_model
• Test Metal Backend / export-model-metal-artifact (mistralai, Voxtral-Mini-3B-2507, quantized-int4-metal) / macos-job (gh)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1
• Test Metal Backend / export-model-metal-artifact (openai, whisper-large-v3-turbo, non-quantized) / macos-job (gh)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1
• Test Metal Backend / export-model-metal-artifact (openai, whisper-large-v3-turbo, quantized-int4-metal) / macos-job (gh)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1

CANCELLED JOB - The following job was cancelled. Please retry:

• pull / test-samsung-models-linux / linux-job (gh)
  ##[error]The operation was canceled.

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