Given a CF template that defines outputs as named exports, I expect the "describe-stack" endpoint to include the exported names. With localstack, that is currently not the case.

Example template:
```yaml
  Outputs:
    VPCId:
      Value: {Ref: MyVPC}
      Export:
        Name: My-VPCId

  Resources:
    MyVPC:
      Properties:
        CidrBlock: 10.0.0.0/16
      Type: AWS::EC2::VPC

```

AWS:
```
$ aws cloudformation describe-stacks
...
                {
                    "OutputKey": "VPCId",
                    "OutputValue": "vpc-0123456789",
                    "ExportName": "My-VPCId"
                },

```

localstack:
```
$ aws cloudformation --endpoint-url=http://localhost:4581/ describe-stacks
...
                {
                    "OutputKey": "VPCId",
                    "OutputValue": "vpc-0123456789"
                },
...
```
if hasattr(entity, 'physical_resource_id'):
        return entity.physical_resource_id
    
    types_with_ref_as_id_or_name = (apigw_models.RestAPI, apigw_models.Resource)
    attr_candidates = ['function_arn', 'Arn', 'Ref', 'id', 'Id', 'name', 'Name']
    for attr in attr_candidates:
        if hasattr(entity, attr):
            if attr in ['id', 'name'] and not isinstance(entity, types_with_ref_as_id_or_name):
                LOG.warning('Unable to find ARN, using "%s" instead: %s - %s',
                            attr, resource_json, entity)
            return getattr(entity, attr)
        if hasattr(entity, 'get_cfn_attribute'):
            try:
                result = entity.get_cfn_attribute(attr)
                if result:
                    return result
            except Exception:
                pass
    
    if hasattr(entity, 'params'):
        for key, value in (entity.params or {}).items():
            if key.endswith('Name'):
                return value
def convert_objs_to_ids(resource_json):