[ET-VK][qconv] Add layout-flexible impl of quantized depthwise conv2d

[SS-JIA]

Stack from ghstack (oldest at bottom):

• [ET-VK][qconv] Add flexible layout impl for im2col #17249
• [ET-VK][qconv] Add flexible layout impl for quantized pointwise conv #17221
• [ET-VK][testing] Create dedicated test binary for pointwise convolutions #17220
• [ET-VK][qconv] Add layout-agnostic general shader for quantized conv #17219
• [ET-VK][quantization] Add layout-flexible clone for int8x4 tensors #17171
• -> [ET-VK][qconv] Add layout-flexible impl of quantized depthwise conv2d #17108
• [ET-VK][ez] Implement helper functions to get fastest moving dim #17107
• [ET-VK][quantization] Implement layout-flexible quantize/dequantize operators #17106
• [ET-VK] Add alignment fields to PackedDimInfo for padded size calculation #17170
• [ET-VK][testing] Add per-shader timing breakdown to benchmark output #17105

Adds a new layout-agnostic quantized depthwise convolution operator
etvk.q8ta_conv2d_dw that uses BufferMetadata and layout specialization
constants to support arbitrary memory layouts (contiguous, channels-last,
4W4C block-packed, etc.).

Key changes:

1. New shader q8ta_conv2d_dw.glsl:

   • Uses BufferMetadata for input/output tensor addressing
   • Layout-aware via inp_layout/outp_layout specialization constants
   • Processes 4 adjacent width positions × 4 channels per thread (4Wx4C tile)
   • Includes optimized paths for simple layouts (outer_block_size == 1)

2. New indexing utilities in indexing.glslh:

   • texel_idx_to_tensor4d_idx(): converts linear texel index to 4D tensor coords
   • tensor4d_idx_to_texel_idx(): converts 4D tensor index to texel index

3. Code refactoring:

   • Extract Conv2DParams struct and create_conv2d_params() to ConvolutionUtils.h
   • Create Q8taConv2dDW.cpp with new operator implementation
   • Add Q8taConv2d.h with public API declarations
   • Move prepack_quantized_conv2d_dw_weight() to new implementation file

4. New workgroup size helpers:

   • pick_q8ta_conv2d_dw_global_wg_size(): computes {W4, H, C4} dispatch size
   • pick_q8ta_conv2d_dw_local_wg_size(): adaptive local size based on tensor dims

5. Test updates:

   • Rename test to test_q8_conv2d_dw.cpp
   • Add TestQ8taConv2d.cpp with shared test utilities

Differential Revision: D92061368

[pytorch-bot]

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❌ 2 New Failures, 1 Pending, 3 Unrelated Failures

As of commit ac864d9 with merge base 1cffd23 ():

NEW FAILURES - The following jobs have failed:

• pull / unittest / linux / linux-job (gh)
  RuntimeError: Command docker exec -t 1e8e61258106288c408d09198073f2658350039fbb42fdae4c5b0690f969af6e /exec failed with exit code 1
• pull / unittest-editable / linux / linux-job (gh)
  RuntimeError: Command docker exec -t ac4c54d9d2baac290a3ad7a4a1bd3639242e7142ddad5b6755a629c51fde7192 /exec failed with exit code 1

BROKEN TRUNK - The following jobs failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / test-samsung-quantmodels-linux / linux-job (gh) (trunk failure)
  ##[error]The operation was canceled.
• pull / unittest / macos / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1
• pull / unittest-editable / macos / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1

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