Adding c10d ops and additional aten ops for DTensor and FSDP2

[komikndr]

Preliminary pull request adding FP8 operators to support Raylight custom nodes.

The c10d operators will not be touched during a normal Comfy run, sincen as far as I know only Raylight uses DTensor and its operators, which require an initialized distributed process group. Normal ComfyUI/main.py execution does not initialize this.

The operators being added:

c10d

• all_gather_into_tensor
• broadcast_
• wait_tensor
• scatter_

aten

• slice
• split
• new_zeros
• as_strided
• cat
• alias

In practice, for c10d only all_gather_into_tensor and wait_tensor are currently required, since wait_tensor is needed for the FSDP unshard path where an in-place copy cannot directly transfer a QuantizedTensor into an unquantized tensor.

To use this inside a model, the nn.Module cannot inherit from a "disable init weight" operator, since every sharded parameter must be properly accounted for.