### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

Lambda refs get lost

### Expected Behavior

Lambda refs work in state machines

### 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)

    awslocal s3 mb s3://mybucket


### Environment

```markdown
- OS: 
- LocalStack:
```


### Anything else?

This is based on a conversation I had with @dominikschubert 
from localstack.services.cloudformation.deployment_utils import PLACEHOLDER_RESOURCE_NAME
from localstack.services.cloudformation.service_models import GenericBaseModel
from localstack.utils.aws import aws_stack
class SFNActivity(GenericBaseModel):
    @staticmethod
    def cloudformation_type():
        return "AWS::StepFunctions::Activity"
    def fetch_state(self, stack_name, resources):
        activity_arn = self.physical_resource_id
        if not activity_arn:
            return None
        client = aws_stack.connect_to_service("stepfunctions")
        result = client.describe_activity(activityArn=activity_arn)
        return result
    @staticmethod
    def get_deploy_templates():
        return {
            "create": {
                "function": "create_activity",
                "parameters": {"name": ["Name", PLACEHOLDER_RESOURCE_NAME], "tags": "Tags"},
            },
            "delete": {
                "function": "delete_activity",
                "parameters": {"activityArn": "PhysicalResourceId"},
            },
        }
class SFNStateMachine(GenericBaseModel):