NXP backend: Add option to use the new Neutron flow.

[MartinPavella]

Summary

The new Neutron C flow is based on MLIR, and it provides improved support for many operators. This PR adds to option to use it.

Test plan

Unit test provided.

cc @robert-kalmar @JakeStevens @digantdesai

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/18998

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❌ 2 New Failures, 2 Unrelated Failures

As of commit 8e2381f with merge base 490ec5c ():

NEW FAILURES - The following jobs have failed:

• pull / test-qnn-buck-build-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 8cf2e0ac94811fea6da6f8a036c83ac255aaf17f58ce964e91dbbb8f8a7e9b1c /exec failed with exit code 3
• pull / test-qnn-passes-linux / linux-job (gh)
  backends/qualcomm/tests/test_passes.py::TestPasses::test_mha_to_sha

BROKEN TRUNK - The following jobs failed but were 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.

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[MartinPavella]

@novak-vaclav @roman-janik-nxp @StrycekSimon feel free to base the enablement of new operators on this PR.
It will not be merged until we migrate to Neutron SDK 3.1.0. For now, new additions based on this SDK will be stored as draft PRs.