Arm backend: Use TOSA-context when adding passes

[oscarandersson8218]

Make sure to be inside TosaLoweringContext when adding/initializing passes. This is needed as passes may try to set self.shape_env using get_context_shape_env(). This patch also uses _get_shape_env_from_gm instead of graph_module.shape_env as we cannot rely on the shape_env being set in the graph_module even though sym-ints are present in the graph.

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

[pytorch-bot]

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❌ 4 New Failures, 2 Cancelled Jobs, 4 Unrelated Failures

As of commit 6c74b96 with merge base 87e65ac ():

NEW FAILURES - The following jobs have failed:

• trunk / test-huggingface-transformers-macos (qwen3-0.6b|coreml_fp32_gpu|--quantize) / macos-job (gh)
  RuntimeError: Command bash /Users/runner/work/_temp/exec_script failed with exit code 1
• trunk / test-torchao-huggingface-checkpoints (lfm2_5_1_2b, linux.arm64.2xlarge, executorch-ubuntu-22.04-g... / linux-job (gh)
  RuntimeError: Command docker exec -t 5ccce72a956dd697f2aadb6935d8fd6b1cd209f5a44f55321cf37cc37e49818f /exec failed with exit code 1
• trunk / test-torchao-huggingface-checkpoints (phi_4_mini, linux.arm64.2xlarge, executorch-ubuntu-22.04-gc... / linux-job (gh)
  RuntimeError: Command docker exec -t 20955956d1ce8ec4e6d4ae570ac2a39ee927dffb082c516ac6cbc93119ffedcf /exec failed with exit code 1
• trunk / test-torchao-huggingface-checkpoints (qwen3_4b, linux.arm64.2xlarge, executorch-ubuntu-22.04-gcc1... / linux-job (gh)
  RuntimeError: Command docker exec -t 75fd77dc39d875bb2a51ef32696e4e44a42792268eaa7ec11f920cc016d5d8b4 /exec failed with exit code 1

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

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

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

• pull / test-models-linux (ic4, portable, linux.4xlarge.memory) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)

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

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

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

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[zingo]

@digantdesai / @GregoryComer this adds timeout to the global suite (not only Arm) so we assume you want to signoff on this :)

[oscarandersson8218]

Unrelated failures.