NXP backend: Unify ExecuTorch and Neutron data format enums.

[MartinPavella]

Summary

Originally, the NXP backend used the NodeFormat enum to mark data formats (memory layouts) of ExecuTorch nodes, and the TensorFormat enum was used to mark the formats for Neutron IR tensors. However, these two classes fundamentally represent the same thing, and there is no need to keep them separated. Additionally, sometimes it was confusing as for which class to use which could result (and has resulted) in bugs.

This PR unifies these 2 enums into 1.

Test plan

N/A

cc @robert-kalmar @JakeStevens @digantdesai

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/17066

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❌ 1 New Failure

As of commit 769ae19 with merge base d001896 ():

NEW FAILURE - The following job has failed:

• pull / test-models-linux (mobilebert, xnnpack-quantization-delegation, linux.2xlarge) / linux-job (gh)
  RuntimeError: Command docker exec -t 5ff11533a437ee93078d0183e7d8a69a725e81decd021e8ad3afdec9cb3156f6 /exec failed with exit code 1

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[MartinPavella]

This PR depends on #17002, so only the last commit is relevant.