[slimtensor] Add aoti_torch_copy_ for SlimTensor

[Gasoonjia]

Stack from ghstack (oldest at bottom):

• rename slimtensor fiies to consistent with executorch files #16469
• [slimtensor] Add utility functions to common_shims_slim #16457
• [slimtensor] Add storage and device property getters to common_shims_slim #16455
• [slimtensor] Add common_shims_slim with basic property getters #16454
• [slimtensor] Add aoti_torch_item_bool for SlimTensor #16453
• [slimtensor] Add aoti_torch_assign_tensors_out for SlimTensor #16452
• -> [slimtensor] Add aoti_torch_copy_ for SlimTensor #16451
• [slimtensor] Add aoti_torch__reinterpret_tensor for SlimTensor #16450
• [slimtensor] Add aoti_torch_new_tensor_handle for SlimTensor #16449
• [slimtensor] Add aoti_torch_delete_tensor_object for SlimTensor #16448
• [slimtensor] Add SlimTensor-based aoti_torch_empty_strided #16447
• [slimtensor] Add SlimTensor-based aoti_torch_create_tensor_from_blob_v2 #16446
• [slimtensor] Add item() methods with CUDA and CPU support for scalar value extraction #16445
• [slimtensor] Add permute() and reshape() view operations #16444
• [slimtensor] Add as_strided() view operation for tensor reinterpretation #16443
• [slimtensor] Add from_blob() factory function for wrapping external memory #16442
• [slimtensor] Add non-owning storage mode for wrapping external memory #16441
• [slimtensor] Enable CUDA tensor copy #16440
• [slimtensor] Add CUDA slimtensor creation with basic functionality #16439
• [slimtensor] Add CUDA Storage with DeviceTraits and memory allocation #16438
• [slimtensor] Add CUDA DeviceType and extend Device class #16437
• [slimtensor] Add all required dtype support (Int8/16/32/64, Bool, BFloat16) #16399
• [slimtensor] Add factory functions for creating empty CPU tensors #16398
• [slimtensor] Add SlimTensor class with basic properties and CPU copy operation #16385
• [slimtensor] Add SizesAndStrides and dimension utility functions for slimtensor usage #16384
• [slimtensor] Storage and SharedPtr for CPU owning mode #16383
• [slimtensor] Introduce Device and ScalarType headers for SlimTensor minimal support #16382

Add SlimTensor-based aoti_torch_copy_() - Copies data from source tensor to destination tensor. Delegates to SlimTensor's copy_() which handles all device combinations (CPU-CPU, CPU-CUDA, CUDA-CPU, CUDA-CUDA).

Differential Revision: D90126246

[pytorch-bot]

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❗ 1 Active SEVs

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• B200 runners are down due to network issues

❌ 5 New Failures, 3 Unrelated Failures

As of commit 1e2ee90 with merge base fd6fa87 ():

NEW FAILURES - The following jobs have failed:

• pull / test-multimodal-linux (gemma3-4b) / linux-job (gh)
  RuntimeError: Command docker exec -t 6242d46fe7b30740102405a80f1c3913431623caa700bf0c2f70c8a36f810d86 /exec failed with exit code 139
• pull / test-samsung-models-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 41fb765dcb7df05ec1576f151c22ac08a7efd5ee7bba41df98a7a1741a3feb21 /exec failed with exit code 1
• pull / test-samsung-quantmodels-linux / linux-job (gh)
  RuntimeError: Command docker exec -t d080c83497e140bd41f0028c9d392f159613d7d5a48be234d23d0d557ae0282e /exec failed with exit code 1
• Test CUDA Builds / check-all-cuda-builds (gh)
  Process completed with exit code 1.
• Test CUDA Builds / test-model-cuda-e2e (mistralai, Voxtral-Mini-3B-2507, quantized-int4-tile-packed) / linux-job (gh)
  RuntimeError: Command docker exec -t cafdb948c1cb6244b7f43b9660855ae1b38bf7725d2e48eb1599a48fb809a126 /exec failed with exit code 1

FLAKY - The following jobs failed but were likely due to flakiness present on trunk:

• pull / test-models-linux (ic3, portable, linux.2xlarge) / linux-job (gh) (matched linux rule in flaky-rules.json)
  The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.
• Test CUDA Builds / test-executorch-cuda-build-12.9 / linux-job (gh) (detected as infra flaky with no log or failing log classifier)

UNSTABLE - The following job is marked as unstable, possibly due to flakiness on trunk:

• pull / android / run-emulator (gh) (#16137)
  Timeout waiting for emulator to boot.

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