Arm backend: Add TOSA dialect unary elementwise ops

[SaoirseARM]

Summary

Added TOSA dialect operators for:

• ABS
• BITWISE_NOT
• CEIL
• CLZ
• COS
• EXP
• FLOOR
• LOG
• LOGICAL_NOT
• NEGATE
• RECIPROCAL
• RSQRT
• SIN

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

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/20017

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❌ 2 New Failures, 3 Unrelated Failures

As of commit 8b6ca08 with merge base 721e641 ():

NEW FAILURES - The following jobs have failed:

• Test WebGPU Backend / test-webgpu / test-backend-linux (webgpu, models) / linux-job (gh)
  RuntimeError: Command docker exec -t 5430c3e5c3ee33b8f1243e5da5bd136d604839e7b9d7f37bb7e7c78729b0ffb6 /exec failed with exit code 1
• Test WebGPU Backend / test-webgpu / test-backend-linux (webgpu, operators) / linux-job (gh)
  RuntimeError: Command docker exec -t 0fe34c70b8d56b34f99775675ed90638d2d2e18e61ba5d8dc368bec1f823c35a /exec failed with exit code 1

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

• pull / test-qnn-testsuite-linux / test-backend-linux (qnn, models) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)
• trunk / test-arm-backend-ethos-u (test_smaller_stories_llama_tosa) / linux-job (gh) (similar failure)
  ##[error]The operation was canceled.

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

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

• trunk / test-arm-backend-vkml (test_smaller_stories_llama_vkml) / linux-job (gh) (trunk failure)
  ##[error]The operation was canceled.

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[SaoirseARM]

@pytorchbot label ciflow/trunk

[SaoirseARM]

@pytorchbot label 'partner: arm'

[SaoirseARM]

@pytorchbot label "release notes: arm"

[SaoirseARM]

Failures look unrelated.