[ET Device Support] Schema changes: device info on Tensor and buffer-level device array

[Gasoonjia]

Stack from ghstack (oldest at bottom):

• [ET Device Support] DeviceAllocator interface and DeviceAllocatorRegistry #17535
• [ET Device Support] Annotate device attributes of CUDA backend IO tensors cuda device #18080
• [ET Device Support] Propagate device info from TensorSpec into serialized Tensor #18079
• [executorch] Propagate device metadata from partitioner result onto TensorSpecs #18078
• [ET Device Support] TensorImpl carries device info #17534
• -> [ET Device Support] Schema changes: device info on Tensor and buffer-level device array #17533

This diff adds device placement information to the ExecuTorch schema to support representing tensor-level device type information, which will be the basic requirement for the following tensor_parser updates.

This is part of the Phase 1 implementation to make ET device type work E2E without user-specified device placement.

Design doc: https://docs.google.com/document/d/1lwd9BlohmwkN5EEvRulO_b-XnZBwv1nMb5l2K3jfuwA/edit?tab=t.0#heading=h.o6anuvkix4bu

Differential Revision: D93635657

[pytorch-bot]

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❌ 2 New Failures, 1 Cancelled Job

As of commit cf46ff9 with merge base 5db6f22 ():

NEW FAILURES - The following jobs have failed:

• pull / test-multimodal-linux (gemma3-4b) / linux-job (gh)
  RuntimeError: Command docker exec -t ef74e4ce4df3c28706057bfd9c2c963c6558b6d64edfef0e0bbe595a6b6611d3 /exec failed with exit code 139
• Validate Flatbuffer Generation / exir-flatbuffer (gh)
  Process completed with exit code 1.

CANCELLED JOB - The following job was cancelled. Please retry:

• pull / unittest-buck / macos / macos-job (gh)

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[lucylq]

nit: is it worth adding a 'DeviceInfo' dataclass/flatbuffers table if we may expect more device-related data?

[Gasoonjia]

if ok i'd like to keep the current structure. It only has two attributes and there will be no other places using device_info.

[JacobSzwejbka]

Review automatically exported from Phabricator review in Meta.

[JacobSzwejbka]

Review automatically exported from Phabricator review in Meta.