`stepfunctions.steps.states.State.output()` doesn't seem to respect result_path

Hello,

there seems to be an issue if `stepfunctions.steps.states.State.output()` is used together with `result_path`. For example:

```
lambda_state_first = LambdaStep(
state_id="MyFirstLambdaStep",
parameters={
"FunctionName": "MakeApiCall",
"Payload": {
"input": "20192312"
}
},
result_path="$.NewOutputPath"
)

lambda_state_first.output()["Payload"].to_jsonpath()
```

I would expect that the output is `"$['NewOutputPath']['Payload']"`, but it's actually `"$['Payload']"`. Is that expected behavior and if so, how is the correct way to use `result_path` together with `output()`?

Thanks!

从 `State.output()` 入口点和 `result_path` 的处理开始，然后使用报告中的 `LambdaStep` 示例重现该问题。跟踪 `output()["Payload"].to_jsonpath()` 的组装过程，并验证是否应用了 result path；当行为得到修正或受支持的用法得到明确记录时，即视为完成。

由索引模型根据 Issue 内容生成。