[ET-VK][ez] Implement helper functions to get fastest moving dim

[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

Add C++ and GLSL helpers to query the fastest moving dimension (the
dimension with stride 1 in buffer layout). This is useful for optimizing
memory access patterns in shaders, as iterating along the fastest moving
dimension maximizes cache locality.

The C++ fastest_whcn_dim() method accounts for block-transposed layouts by
returning outer_packed_dim instead of packed_dim when applicable. A
corresponding GLSL macro extracts this info from the hashed layout.

Differential Revision: D92061369

[pytorch-bot]

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❌ 4 New Failures, 1 Pending, 3 Unrelated Failures

As of commit 2b6baec with merge base 1cffd23 ():

NEW FAILURES - The following jobs have failed:

• pull / android / run-emulator (gh)
  The process '/usr/bin/sh' failed with exit code 1
• pull / unittest / linux / linux-job (gh)
  RuntimeError: Command docker exec -t d2438cb1cc553f7fe992671b0409422851af8958d8b3fd36ed1733bfb98a7a6a /exec failed with exit code 1
• pull / unittest-editable / linux / linux-job (gh)
  RuntimeError: Command docker exec -t 4183d7acaa2fc28db6d56bb6b2d4eaf6e4ed7d4d36a817dbe90d9fb39982ec56 /exec failed with exit code 1
• Test CUDA Builds / export-model-cuda-artifact (openai, whisper-large-v3-turbo, quantized-int4-tile-packed) / linux-job (gh)
  RuntimeError: Command docker exec -t 5a4655e3b6f1cfeafe0da8aec8421573c8c53a3b1deefd854fd8f2abcced92b6 /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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