NXP backend: Extend tests for linear addmm mm converters add mm quantization

[roman-janik-nxp]

Summary

This PR refactors and extends tests for Addmm and Mm converters. Adds quantization for Mm operator.

Test plan

Unit tests provided.

cc @digantdesai @JakeStevens @robert-kalmar

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/14601

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❌ 3 New Failures

As of commit 88f6c22 with merge base ce6e2cf ():

NEW FAILURES - The following jobs have failed:

• pull / test-qnn-wheel-packages-linux (3.10) / linux-job (gh)
  An error occurred trying to start process '/usr/bin/bash' with working directory '/home/ec2-user/actions-runner/_work/executorch/executorch/pytorch/executorch'. No such file or directory
• pull / test-samsung-models-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 288a2e539ffe36626fdd6decb12b3dd225102dde9d84b37443dc4250b3fed5e6 /exec failed with exit code 1
• pull / unittest-editable / macos / macos-job (gh)
  export/tests/test_target_recipes.py::TestTargetRecipes::test_linear_model

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[roman-janik-nxp]

@pytorchbot label "module: nxp" "release notes: nxp"

[roman-janik-nxp]

There are failing tests for Mm converter in unittest-nxp-neutron, due to unforeseen dependency on Neutron converter 25.09 regarding handling bias tensors. The PR for upgrade to NC 25.09 is already created #14591, so these tests should pass once there is new NC version. For now on hold.

[roman-janik-nxp]

Failing workflows are unrelated to this PR, ready for merge.