Handle out_dtype in ReplacePT2DequantWithCadenceDequantPass (#19743)

[ethansfng]

Summary:

torchao's convert_pt2e adds out_dtype kwargs to dequant nodes for bf16 models. cadence::dequantize_per_tensor doesn't support this kwarg (it hardcodes float32 output), so ReplacePT2DequantWithCadenceDequantPass crashes when it forwards kwargs blindly to the cadence op.

Strip out_dtype from kwargs before creating the cadence dequant node, and insert an aten.to.dtype cast after it to preserve the original output dtype semantics.

Differential Revision: D105630451

[pytorch-bot]

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❌ 1 New Failure, 2 Unrelated Failures

As of commit fa1bce3 with merge base ec76470 ():

NEW FAILURE - The following job has failed:

• pull / test-parakeet-xnnpack-linux / linux-job (gh)
  RuntimeError: Command docker exec -t eb9b99b2ad9e445ac54c2746c536132cee853e4421e864dd4147c42fef77bbbe /exec 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

• pull / unittest / macos / macos-job (gh) (trunk failure)
  ##[error]The operation was canceled.
• pull / unittest-editable / macos / macos-job (gh) (trunk failure)
  ##[error]The operation was canceled.

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