Support input payload generation for tensorrtllm engine

[nv-hwoo]

Generates input json file for PA to directly send requests to tensorrtllm engine:

{
   "data":[
      {
         "input_ids":{
            "content":[
               1243,
               1881,
               697
            ],
            "shape":[
               3
            ]
         },
         "input_lengths":[
            3
         ],
         "request_output_len":[
            256
         ]
      },
      ...
}

[dyastremsky]

Great work!