[ECS] [Fargate]: bug in creation of Task Definition with not acceptable portMappings via AWS Console

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**Tell us about your request**
There is a bug within the [AWS Task Definition](https://us-east-1.console.aws.amazon.com/ecs/home?region=us-east-1#/taskDefinitions) creation console which can be described as follows:

1. Create a Fargate ECS task with portMappings as shown below:

```
"portMappings": [
{
"hostPort": 8080,
"protocol": "tcp",
"containerPort": 80
}
],
```

2. Press "Create"
3. A message will be presented that looks as follows: `Created new revision of Task Definition nginx:51 successfully`.
4. Reopen the new task and the Port Mappings will be shown as follows:
```
"portMappings": [
{
"hostPort": 80,
"protocol": "tcp",
"containerPort": 80
}
],
```

I don't believe this is possible, btw, but the user-interface allows the creation of the configuration above.

**Which service(s) is this request for?**
ECS Fargate

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**

I'm hoping to provide a bug-free experience for users of the ECS Fargate offering who are utilizing the AWS Console to create (or test) ECS Fargate services.

**Are you currently working around this issue?**
We render all of our Task Definitions via CloudFormation/terraform, but there is no workaround for this bug. You enter data one way AWS changes it rather than throws an error.

**Additional context**
There are two files attached to show the bug:

1. Before - Creating nginx-53.png
2. After - Viewing nginx-53.png

**Attachments**
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Before Image - Creation of a New Task Definition

After Image - Viewing The Task Definition