[slimtensor] Add aoti_torch_assign_tensors_out for SlimTensor #5034

Job	Run time
test-executorch-metal-build / macos-job	41s
export-model-metal-artifact (openai, whisper-small, non-quantized) / macos-job	37s
export-model-metal-artifact (mistralai, Voxtral-Mini-3B-2507, non-quantized) / macos-job	36s
export-model-metal-artifact (openai, whisper-large-v3-turbo, non-quantized) / macos-job	31s
test-model-metal-e2e	0s
	2m 25s

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