Arm backend: Add limited support for fish shell in setup_path.sh

[zingo]

Generate both sh and fish shell versions of the setup_path script

cc @digantdesai @freddan80 @per @oscarandersson8218

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/13323

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❌ 8 New Failures, 3 Pending, 1 Unrelated Failure

As of commit c819b2a with merge base 1164fe4 ():

NEW FAILURES - The following jobs have failed:

• Build documentation / build (buck2) / Build doc (gh)
  At least one of the pre-conditions you specified did not hold
• trunk / test-huggingface-transformers-coreml (olmo-1b|coreml_fp32_gpu|--quantize) / macos-job (gh)
  RuntimeError: Command bash /Users/runner/work/_temp/exec_script failed with exit code 1
• trunk / test-huggingface-transformers-coreml (phi4-mini|xnnpack|--quantize) / macos-job (gh)
  RuntimeError: Command bash /Users/runner/work/_temp/exec_script failed with exit code 138
• trunk / test-huggingface-transformers-coreml (smollm2-135m|xnnpack|--quantize) / macos-job (gh)
  RuntimeError: Command bash /Users/runner/work/_temp/exec_script failed with exit code 138
• trunk / test-models-arm-zephyr (add) / linux-job (gh)
  RuntimeError: Command docker exec -t 70df12588fc1ee91b09af1d2ca0496cfe5f9d1a72c20087360a6bf64619e4dca /exec failed with exit code 1
• trunk / test-models-arm-zephyr (mv2) / linux-job (gh)
  RuntimeError: Command docker exec -t e99b0c9bf0ffdc7ba50aec20febac3b4f37cea05f29ac0312e715155f7808a2a /exec failed with exit code 1
• trunk / test-models-arm-zephyr (softmax) / linux-job (gh)
  RuntimeError: Command docker exec -t 4fa0a47192f31524327d710bf446885001dbf44a532ae3d96f105cb5b3357fc9 /exec failed with exit code 1
• trunk / unittest-release / linux / linux-job (gh)
  RuntimeError: Command docker exec -t ef6d59f1879089b8dc185b996b202586f85cb9ee1a143ffbc894f7937a7331b4 /exec failed with exit code 8

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

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

• trunk / unittest-release / macos / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 8

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[zingo]

This should go in after #13369

[zingo]

fails are unrelated