Step Functions - Graph not rendering properly in Parallel state

## Problem

When rendering a definition with certain step types the steps order becomes relevant and the resulting graph becomes incorrect.
This is a bug when rendering the graph. It not only happens on vs code but also on the **Graph view of the AWS console**.

## Steps to reproduce the issue

You can reproduce it parting from the given definition.

```json
{
"StartAt": "ParallelStep",
"States": {
"ParallelStep": {
"Type": "Parallel",
"End": true,
"Branches": [
{
"StartAt": "FIRST_STEP_HERE",
"States": {
"FIRST_STEP_HERE": {
"Next": "SetupIterator",
"Resource": "resource-arn-here",
"Type": "Task"
},
"BeforeDoOperation": {
"Next": "DoOperation",
"Resource": "resource-arn-here",
"Type": "Task"
},
"DoOperation": {
"Next": "IsRejected",
"Resource": "resource-arn-here",
"Type": "Task"
},
"Iterator": {
"Next": "IsIteratorDone",
"Resource": "resource-arn-here",
"Type": "Task"
},
"IsIteratorDone": {
"Choices": [
{
"BooleanEquals": false,
"Variable": "$.variable_name",
"Next": "BeforeDoOperation"
}
],
"Default": "Done",
"Type": "Choice"
},
"Done": {
"End": true,
"Type": "Pass"
},
"IsRejected": {
"Choices": [
{
"BooleanEquals": false,
"Next": "Rejected",
"Variable": "$.variable_name"
}
],
"Default": "Iterator",
"Type": "Choice"
},
"Rejected": {
"Type": "Fail"
},
"SetupIterator": {
"Next": "Iterator",
"Type": "Pass"
}
}
}
]
}
}
}
```

For that given definition the resulting graph is the following:


Until here everything is fine 👍

The problem arise when you're using a tool on top of ASL that moves step ordering.
For instance, here's what happens for almost the same definition. Just moving the `FIRST_STEP_HERE` down one position.

```json
{
"StartAt": "ParallelStep",
"States": {
"ParallelStep": {
"Type": "Parallel",
"End": true,
"Branches": [
{
"StartAt": "FIRST_STEP_HERE",
"States": {
"BeforeDoOperation": {
"Next": "DoOperation",
"Resource": "resource-arn-here",
"Type": "Task"
},
"FIRST_STEP_HERE": {
"Next": "SetupIterator",
"Resource": "resource-arn-here",
"Type": "Task"
},
"DoOperation": {
"Next": "IsRejected",
"Resource": "resource-arn-here",
"Type": "Task"
},
"Iterator": {
"Next": "IsIteratorDone",
"Resource": "resource-arn-here",
"Type": "Task"
},
"IsIteratorDone": {
"Choices": [
{
"BooleanEquals": false,
"Variable": "$.variable_name",
"Next": "BeforeDoOperation"
}
],
"Default": "Done",
"Type": "Choice"
},
"Done": {
"End": true,
"Type": "Pass"
},
"IsRejected": {
"Choices": [
{
"BooleanEquals": false,
"Next": "Rejected",
"Variable": "$.variable_name"
}
],
"Default": "Iterator",
"Type": "Choice"
},
"Rejected": {
"Type": "Fail"
},
"SetupIterator": {
"Next": "Iterator",
"Type": "Pass"
}
}
}
]
}
}
}
```

As you can see in the graph below ⬇️ Now it's totally incorrect and apparently nothing calls the `FIRST_STEP_HERE` ❓

Now, if you want to broke the graph just do some more ordering changes:

```json
{
"StartAt": "ParallelStep",
"States": {
"ParallelStep": {
"Type": "Parallel",
"End": true,
"Branches": [
{
"StartAt": "FIRST_STEP_HERE",
"States": {
"BeforeDoOperation": {
"Next": "DoOperation",
"Resource": "resource-arn-here",
"Type": "Task"
},
"FIRST_STEP_HERE": {
"Next": "SetupIterator",
"Resource": "resource-arn-here",
"Type": "Task"
},
"DoOperation": {
"Next": "IsRejected",
"Resource": "resource-arn-here",
"Type": "Task"
},
"Iterator": {
"Next": "IsIteratorDone",
"Resource": "resource-arn-here",
"Type": "Task"
},
"IsIteratorDone": {
"Choices": [
{
"BooleanEquals": false,
"Variable": "$.variable_name",
"Next": "BeforeDoOperation"
}
],
"Default": "Done",
"Type": "Choice"
},
"SetupIterator": {
"Next": "Iterator",
"Type": "Pass"
},
"Done": {
"End": true,
"Type": "Pass"
},
"IsRejected": {
"Choices": [
{
"BooleanEquals": false,
"Next": "Rejected",
"Variable": "$.variable_name"
}
],
"Default": "Iterator",
"Type": "Choice"
},
"Rejected": {
"Type": "Fail"
}
}
}
]
}
}
}
```

## Expected behavior

So, given the [language specification](https://states-language.net/spec.html) and as far as I understand ordering shouldn’t be a factor to determine state machine functionality and in fact, if you test this flow, it works as expected so there's a mismatch between the logic and the rendering.

I must also mention that there's a weird combination of step types what produce this error. If you play with the provided definition you may notice that if you remove the `Choice` or the `Done` step, or just if you get the code out of the parallel state everything works fine. I think even if you remove the `BeforeDoOperation` step everything works just perfectly.

## System details (run the `AWS: About Toolkit` command)

- OS: MacOS 12.3.1
- Visual Studio Code version: 1.67.2
- AWS Toolkit version: v1.38.0

Reproduce the issue in the VS Code AWS Toolkit Graph view using the provided Parallel state definitions, changing only the order of States entries. Trace the graph-rendering path responsible for Parallel states and Choice/Pass/Fail combinations; done means equivalent definitions render the same graph regardless of state ordering, with coverage for the supplied cases.

Written by the indexing model from the issue text.