[et device 1/n] introduce cuda device type

[pytorchbot]

This PR was created by the merge bot to help merge the original PR into the main branch.
ghstack PR number: #17400 by @Gasoonjia
^ Please use this as the source of truth for the PR details, comments, and reviews
ghstack PR base: https://github.com/pytorch/executorch/tree/gh/gasoonjia/118/base
ghstack PR head: https://github.com/pytorch/executorch/tree/gh/gasoonjia/118/head
Merge bot PR base: https://github.com/pytorch/executorch/tree/main
Merge bot PR head: https://github.com/pytorch/executorch/tree/gh/gasoonjia/118/orig
Differential Revision: D92928772
@diff-train-skip-merge

[pytorch-bot]

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🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/17427

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❌ 3 New Failures

As of commit 6413c57 with merge base c09db81 ():

NEW FAILURES - The following jobs have failed:

• pull / test-multimodal-linux (gemma3-4b) / linux-job (gh)
  RuntimeError: Command docker exec -t 04e7f39bf118aad279293eabed59b5ae4ebfcf94b7862a6ca2279deeecdd298a /exec failed with exit code 139
• pull / test-samsung-models-linux / linux-job (gh)
  test_inception_v3_fp16
• Test CUDA Builds / test-model-cuda-e2e (mistralai, Voxtral-Mini-3B-2507, quantized-int4-tile-packed) / linux-job (gh)
  RuntimeError: Command docker exec -t f14bdbb090fa12735a9c4b9f20b018340db4a1895071630049b0538ed2fe45d5 /exec failed with exit code 1

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