Allow Array of Services in IAM Role for Tasks and Build

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**Tell us about your request**

The current AppRunner interface in the AWS console appears to query the IAM endpoint and return a list of all IAM roles, and them somehow review those roles with statements that allow the service principals of tasks or build (.apprunner.amazonaws.com) to be used. If these two principals are listed as a list, the UI will not populate them.

**Describe alternatives you've considered**
Separating the Principals works as expected.

**Additional context**

This trust does not allow the IAM role to be populated in the UI.
```
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "",
"Effect": "Allow",
"Principal": {
["tasks.apprunner.amazonaws.com","build.apprunner.amazonaws.com"]
},
"Action": "sts:AssumeRole"
}
]
}
```

Whereas the same effective policy as two blocks works as expected.

```
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "",
"Effect": "Allow",
"Principal": {
"Service": "tasks.apprunner.amazonaws.com"
},
"Action": "sts:AssumeRole"
},
{
"Sid": "build",
"Effect": "Allow",
"Principal": {
"Service": "build.apprunner.amazonaws.com"
},
"Action": "sts:AssumeRole"
}
]
}
```

**Attachments**

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