NXP backend: Enable MM and AddMM with new Neutron flow.

[MartinPavella]

Summary

This PR enables the MM and AddMM operators in the NXP backend using the new Neutron C MLIR flow.

Test plan

Unit tests provided.

cc @robert-kalmar @JakeStevens @digantdesai @rascani

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/20278

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❌ 4 New Failures

As of commit 9c886de with merge base e88fd04 ():

NEW FAILURES - The following jobs have failed:

• Cadence Build & Test / hifi-build / hifi4 (gh)
  Input required and not supplied: aws-region
• Cadence Build & Test / vision-build / vision (gh)
  Input required and not supplied: aws-region
• pull / unittest-editable / linux / linux-job (gh)
  examples/models/test/test_export.py::ExportTest::test_efficient_sam_export_to_executorch
• pull / unittest-nxp-neutron / linux-job (gh)
  RuntimeError: Command docker exec -t 5244c8a9df7eccaa78e3c78de78fc3c33c992fee21b4d1a40c538a8c5cfca0dc /exec failed with exit code 1

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[MartinPavella]

@novak-vaclav, @irtrukhina please feel free to have a look as well.