Arm backend: Decompose where.ScalarOther for quantization support

[YufengShi-dudu]

Arm quantizer does not annotate aten.where.ScalarOther, so where remains unquantized after it is rewritten to aten.where.self pre-QUANTIZE.

Decompose where.ScalarOther(cond, x, s) into where.self(cond, x, full_like(x, s)) before QUANTIZE so existing where.self annotation can handle it.

Change-Id: I82a7ffec5e3e037219ab7185d71371c7c14a5b4f

cc @digantdesai @freddan80 @per @zingo @oscarandersson8218 @mansnils @Sebastian-Larsson @robell

[pytorch-bot]

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❌ 2 New Failures, 1 Cancelled Job, 11 Pending, 15 Unrelated Failures

As of commit 026943b with merge base 884ace9 ():

NEW FAILURES - The following jobs have failed:

• Build Presets / windows (pybind) / build (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• pull / unittest-editable / macos / macos-job (gh)
  export/tests/test_target_recipes.py::TestTargetRecipes::test_mv3_model

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

• trunk / test-mcu-cortex-m-backend / linux-job (gh)
  ##[error]The operation was canceled.

FLAKY - The following jobs failed but were likely due to flakiness present on trunk:

• trunk / test-models-windows (resnet50, portable) / windows-job (gh) (similar failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (resnet50, xnnpack-q8) / windows-job (gh) (similar failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (vit, portable) / windows-job (gh) (similar failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1

BROKEN TRUNK - The following jobs failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• Build Presets / windows (windows) / build (gh) (trunk failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• pull / unittest / windows / windows-job (gh) (trunk failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• pull / unittest-editable / windows / windows-job (gh) (trunk failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (emformer_transcribe, portable) / windows-job (gh) (trunk failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (emformer_transcribe, xnnpack-q8) / windows-job (gh) (trunk failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (mobilebert, portable) / windows-job (gh) (trunk failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (mobilebert, xnnpack-q8) / windows-job (gh) (trunk failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (mv3, portable) / windows-job (gh) (trunk failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (mv3, xnnpack-q8) / windows-job (gh) (trunk failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (vit, xnnpack-q8) / windows-job (gh) (trunk failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / unittest-release / windows / windows-job (gh) (trunk failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• Windows MSVC Build / build-windows-msvc / windows-job (gh) (trunk failure)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1

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