[Arm backend] Refactor runner_utils, removing RunnerUtil

[Erik-Lundell]

As the execution of models on reference_model
or on FVP has simplified, there is no longer need
for a class to handle the execution.
Instead, running a model should should only be a
function call with the model, inputs and some metadata. This makes it easier to reuse runner_utils.

Change-Id: Ib6addbdaa2fa492c356e92ad1b95c2dac2885b9d

cc @digantdesai @freddan80 @per @zingo @oscarandersson8218

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/7722

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

As of commit dd6e47e with merge base fedb035 ():

NEW FAILURE - The following job has failed:

• pull / test-phi-3-mini-runner-linux / linux-job (gh)
  RuntimeError: Command docker exec -t f3aefe1438ba2df61ba66b285cbf31f9b78e930959995ccc90d363c3cb504d9e /exec failed with exit code 2

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

• trunk / test-llama-runner-mac (fp32, portable) / macos-job (gh)
  ##[error]The operation was canceled.
• trunk / test-models-macos (cmake, ic3, portable, macos-m1-stable, 90) / macos-job (gh)
  ##[error]The operation was canceled.
• trunk / test-models-macos (cmake, llama3_2_vision_encoder, portable, macos-m1-stable, 90) / macos-job (gh)
  ##[error]The operation was canceled.
• trunk / test-models-macos (cmake, resnet18, xnnpack-quantization-delegation, macos-m1-stable, 90) / macos-job (gh)
  ##[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-models-macos (cmake, emformer_transcribe, xnnpack-quantization-delegation, macos-m1-stable, 90) / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1

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[Erik-Lundell]

Unrelated ci failure.