Arm backend: Add docstrings for tosa/specification.py

[Sebastian-Larsson]

cc @digantdesai @freddan80 @per @zingo @oscarandersson8218

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/14536

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❌ 5 New Failures, 5 Unrelated Failures

As of commit 1f4bf1a with merge base b3f3111 ():

NEW FAILURES - The following jobs have failed:

• pull / test-qnn-wheel-packages-linux (3.10) / linux-job (gh)
  RuntimeError: Command docker exec -t 3fec727f36e80228db5e4b3a5fb8fa57ed188894385af4f7df16f21f6eeed74f /exec failed with exit code 1
• pull / test-qnn-wheel-packages-linux (3.11) / linux-job (gh)
  RuntimeError: Command docker exec -t b5467be4fb1ae308263235758e6ae97be7f88252c62a928dc22359367e4bb2e9 /exec failed with exit code 1
• pull / test-qnn-wheel-packages-linux (3.12) / linux-job (gh)
  RuntimeError: Command docker exec -t 6b099f55ae8a3e5c1e8a65b92ee1f798b28d344b16519bf01f922b4eecdf54c0 /exec failed with exit code 1
• pull / test-samsung-models-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 1239424cb5ff119e413a546263db2616c35d9dc74a8724fe5b4bd8d0a3a3daaf /exec failed with exit code 1
• trunk / test-qnn-optimum-model (fp32, roberta) / linux-job (gh)
  RuntimeError: Command docker exec -t dda13e43985e44edde44ba1fad1969969e42721978f9e5d0ceaf013d6ada6d45 /exec failed with exit code 1

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

• pull / test-binary-size-linux-gcc / linux-job (gh) (similar failure)
  ##[error]The operation was canceled.
• pull / unittest-editable / macos / macos-job (gh) (similar failure)
  exir/tests/test_quant_fusion_pass.py::TestQuantFusionPass::test_embedding_torchao

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

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

• pull / test-setup-linux-gcc / linux-job (gh) (trunk failure)
  ##[error]The operation was canceled.
• pull / unittest / macos / macos-job (gh) (trunk failure)
  exir/tests/test_quant_fusion_pass.py::TestQuantFusionPass::test_embedding_torchao
• trunk / unittest-release / macos / macos-job (gh) (trunk failure)
  exir/tests/test_quant_fusion_pass.py::TestQuantFusionPass::test_embedding_torchao

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[zingo]

trunk / test-arm-backend (test_pytest_ops_ethosu_fvp) / linux-job (push)Failing after 115m
rerun test