Re-support kwargs at run time

[kwen2501]

People would like to pass kwargs to model as in non-pipeline runs, instead of converting it to args tuple first.
See: huggingface/accelerate#2345

args = (
    example_inputs["input_ids"].to("cuda:0"),
    example_inputs["decoder_input_ids"].to("cuda:0")
)
with torch.no_grad():
    output = model(*args)

PiPPy used to support kwargs before tracer migration. We'd need to add it back.