### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

When attempting to list roles where permission boundaries are attached the response cannot be serialized 

`aws --endpoint-url=http://localhost:4566 iam list-roles --region ap-southeast-2`
```
An error occurred (InternalError) when calling the ListRoles operation (reached max retries: 2): exception while calling iam.ListRoles: Invalid type when serializing AttachedPermissionsBoundary: '<Element 'member' at 0xffff8275ef20>' cannot be parsed to structure.
```

### Expected Behavior

Expect that all roles are listed

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

    docker run localstack/localstack

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

* Create an IAM policy
* Create an IAM role which used the policy as a permission boundary
* Attempt to list all roles with `aws --endpoint-url=http://localhost:4566 iam list-roles --region ap-southeast-2`


### Environment

```markdown
- OS: MacOS
- LocalStack: latest
```


### Anything else?

_No response_
import json
from datetime import datetime
from typing import Dict, List, Optional
from urllib.parse import quote
from moto.iam.models import AccessKey, AWSManagedPolicy, IAMBackend, InlinePolicy, Policy
from moto.iam.models import Role as MotoRole
from moto.iam.models import filter_items_with_path_prefix, iam_backends
from moto.iam.policy_validation import VALID_STATEMENT_ELEMENTS
from localstack import config
from localstack.aws.api import CommonServiceException, RequestContext, handler
from localstack.aws.api.iam import (
    ActionNameListType,
    ActionNameType,
    AttachedPermissionsBoundary,
    ContextEntryListType,
    CreateRoleRequest,
    CreateRoleResponse,
    CreateServiceLinkedRoleResponse,
    CreateUserResponse,
    DeleteServiceLinkedRoleResponse,
    DeletionTaskIdType,
    DeletionTaskStatusType,
    EvaluationResult,
    GetServiceLinkedRoleDeletionStatusResponse,
    GetUserResponse,
    IamApi,
    ListInstanceProfileTagsResponse,