Fixing issues with using buffers for quantized linear weights.

[trivedivivek]

Summary:
This diff issues related to using buffers for quantized linear weights in the Executorch Vulkan backend.

The changes include:

• Using uint for buffer weight storage instead of uint8 and packing / unpacking integer values accordingly.
• Updating the shader parameters in QuantizedLinearQCSNW.cpp to include the correct sizes for the packed weights.

Differential Revision: D84870681

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/15306

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❌ 8 New Failures, 1 Pending, 2 Unrelated Failures

As of commit ca24759 with merge base 6e08aef ():

NEW FAILURES - The following jobs have failed:

• pull / test-samsung-models-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 4995cb6e4a243e4abc3ad1f50809cf1812fa4d3c2df70c7492be293dd092274a /exec failed with exit code 1
• pull / unittest-nxp-neutron / linux-job (gh)
  RuntimeError: Command docker exec -t f9f1515effe3670c8e4d582cf8e048ea832ee933def4dbdf2b0d767acee3b08f /exec failed with exit code 1
• Test CUDA Builds / export-gemma3-cuda-non-quantized / linux-job (gh)
  RuntimeError: Command docker exec -t 04b457b5211c13dca963f50f53dd3c8ae4aab592adc0d8bbc39a31a9cf690dae /exec failed with exit code 2
• Test CUDA Builds / export-gemma3-cuda-quantized-int4-tile-packed / linux-job (gh)
  RuntimeError: Command docker exec -t 8e34b0b3dfd35933a29dbc087c40d0b20b4b2678d07332f077818fb30ead1659 /exec failed with exit code 2
• Test CUDA Builds / export-voxtral-cuda-non-quantized / linux-job (gh)
  RuntimeError: Command docker exec -t ef864fe618bc38ac1f7f1771b53ff7ec28e10188be24b97da878edd812d2fb40 /exec failed with exit code 2
• Test CUDA Builds / export-voxtral-cuda-quantized-int4-tile-packed / linux-job (gh)
  RuntimeError: Command docker exec -t ecc7194bb7fd832ab1379b7b26c7c341bee962cbcbd63ef1acdcc8874ee0dd0c /exec failed with exit code 2
• Test CUDA Builds / export-voxtral-cuda-quantized-int4-weight-only / linux-job (gh)
  RuntimeError: Command docker exec -t dc8192da79460c4540a145e263e32c9efde2fb08a3484493865981fc56c5e9a1 /exec failed with exit code 2
• Test Metal Backend / export-voxtral-metal-artifact / macos-job (gh)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 2

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 / linux / linux-job (gh) (trunk failure)
• pull / unittest-editable / linux / linux-job (gh) (trunk failure)

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

[meta-codesync]

@trivedivivek has exported this pull request. If you are a Meta employee, you can view the originating Diff in D84870681.