`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!

Start with the `State.output()` entry point and the `result_path` handling, then reproduce the issue using the `LambdaStep` example in the report. Trace how `output()["Payload"].to_jsonpath()` is assembled and verify whether the result path is applied; done means the behavior is corrected or the supported usage is clearly documented.

Written by the indexing model from the issue text.