Qualcomm AI Engine Direct - Support floor_divide with int input in QNN HTP backend

[pytorchbot]

Summary

• Since QNN does not support floor_divide operations for int32 or int64 inputs, it is necessary to decompose the operation into a division using floating-point precision, followed by applying the floor function.

Test plan

UT added

Author: @shewu-quic

cc @cccclai @shewu-quic @haowhsu-quic @DannyYuyang-quic @cbilgin

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/15120

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❌ 1 New Failure, 3 Cancelled Jobs, 1 Unrelated Failure

As of commit 5a622b7 with merge base e0dda90 ():

NEW FAILURE - The following job has failed:

• Lint / lintrunner-mypy / linux-job (gh)
  >>> Lint for docs/source/conf.py:

CANCELLED JOBS - The following jobs were cancelled. Please retry:

• pull / unittest / macos / macos-job (gh)
  ##[error]The operation was canceled.
• pull / unittest-editable / macos / macos-job (gh)
  ##[error]The operation was canceled.
• Test CoreML Backend / test-coreml / test-backend-macos (coreml_static_int8, operators) / macos-job (gh)
  ##[error]The operation was canceled.

FLAKY - The following job failed but was likely due to flakiness present on trunk:

• pull / unittest-arm-backend-with-no-fvp (test_pytest_models) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)

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