Enable the CPU int4 with HQQ quant

[leslie-fang-intel]

Summary

This PR introduces two main changes:

• Enables WOQ int4 accuracy testing on CPU, which was previously skipped.

• Adds Int4CPULayout to support HQQ raw output and includes corresponding tests to resolve TorchAO int4 hqq quant has accuracy issue on CPU #1823

Test Plan

python -u -m pytest -s -v test/quantization/test_quant_api.py -k test_int4wo_cpu
python -u -m pytest -s -v test/integration/test_integration.py -k test_int4_weight_only_hqq_quant_subclass_api

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/ao/1824

• 📄 Preview Python docs built from this PR

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❌ 1 New Failure

As of commit 6c3710b with merge base 1c76736 ():

NEW FAILURE - The following job has failed:

• Run TorchAO Experimental Tests / test (macos-14) (gh)
  Process completed with exit code 127.

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[leslie-fang-intel]

The CI failure [Run TorchAO Experimental Tests / test (macos-14) seems also happening in other PRs.