Plumbing for Arm Example Runnner to use Zephyr Toolchain

[BujSet]

Summary

Once setup.sh and PATH have been set to point to Arm Zephyr toolchain, the run.sh script and its child processes must use the specified toolchain. This change adds the plumbing needed to support this. A new file, examples/arm/ethos-u-setup/arm-zephyr-eabi-gcc.cmake is introduced to make the command line options easy and consistent.

Test plan

After picking the changes in this PR, the following can be run to produce the same results as in the Arm Ethos-U tutorial, now utilizing the Arm Zephyr toolchain instead of the bare metal:

examples/arm/run.sh --toolchain=arm-zephyr-eabi-gcc --model_name=add --no_quantize --target=ethos-u55-128

Which still produces the following output:

I [executorch:arm_executor_runner.cpp:747 main()] Model executed successfully.
I [executorch:arm_executor_runner.cpp:751 main()] 1 outputs:
Output[0][0]: (int) 2
Output[0][1]: (int) 2
Output[0][2]: (int) 2
Output[0][3]: (int) 2
Output[0][4]: (int) 2
I [executorch:arm_executor_runner.cpp:874 main()] Program complete, exiting.
I [executorch:arm_executor_runner.cpp:878 main()] ♦
Info: /OSCI/SystemC: Simulation stopped by user.
[warning ][main@0][3440 ns] Simulation stopped by user
[backends/arm/scripts/run_fvp.sh] Simulation complete, 0
Checking for problems in log:
No problems found!
+ set +x

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/12078

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

As of commit 8b18e8b with merge base 2a2d757 ():

NEW FAILURE - The following job has failed:

• Lint / lintrunner / linux-job (gh)
  >>> Lint for backends/arm/_passes/replace_scalar_with_tensor_pass.py:

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

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

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

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

• Apple / build-benchmark-app / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/runner/work/_temp/exec_script failed with exit code 65
• pull / unittest / linux / linux-job (gh) (trunk failure)
  examples/models/llama/tests/test_ring_attention.py::TestRingAttention::test_single_token_processing_quantized
• pull / unittest-editable / linux / linux-job (gh) (trunk failure)
  examples/models/llama/tests/test_ring_attention.py::TestRingAttention::test_single_token_processing_quantized
• trunk / unittest-release / linux / linux-job (gh) (trunk failure)
  examples/models/llama/tests/test_ring_attention.py::TestRingAttention::test_single_token_processing_quantized

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[BujSet]

@pytorchbot label "release notes: none"

[BujSet]

@digantdesai @zingo @perheld Similar to the PR here. This PR splits part of the Arm Zephyr cmake Preset PR. This PR relates to the changes need for the run.sh script.

cc @larryliu0820