CUDA: Do not mutate cgraph for fused ADDs (llama/19566)

CUDA: Do not mutate cgraph for fused ADDs (llama/19566)

* Do not mutate cgraph for fused ADDs

1. We should try to minimize in-place changes to the incoming
   ggml_cgraph where possible (those should happen in graph_optimize)
2. Modifying in-place leads to an additional, unnecessary graph capture
   step as we store the properties before modifying the graph in-place
   in the cuda-backend

* Assert ggml_tensor is trivially copyable

* Update ggml/src/ggml-cuda/ggml-cuda.cu

Co-authored-by: Aman Gupta <redacted>
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Co-authored-by: Aman Gupta <redacted>