### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

Currently the VTL template for `request_templates` is not processed properly:

```
#set( $body = $input.json("$") )

#macro( loop $map )
{
    #foreach($key in $map.keySet())
        #set( $k = $util.escapeJavaScript($key) )
        #set( $v = $util.escapeJavaScript($map.get($key)).replaceAll("\\'", "'") )
        "$k": "$v"
        #if( $foreach.hasNext ) , #end
    #end
}
#end

{
    "enhancedAuthContext": #loop($context.authorizer),

    "headers": #loop($input.params().header),

    "query": #loop($input.params().querystring),

    "path": #loop($input.params().path),

    "identity": #loop($context.identity),

    "stageVariables": #loop($stageVariables),
}
EOF
}
```

results in,

```
'

{
    "enhancedAuthContext": {
    }
,

    "headers": {
    }
,

    "query": {
    }
,

    "path": {
    }
,

    "identity": {
    }
,

    "stageVariables": {
    }
,
}
'
```

### Expected Behavior

The template should be rendered and have the JSON properties.

### How are you starting LocalStack?

Custom (please describe below)

### 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: MacOS
- LocalStack: 0.14
```


### Anything else?

This example can be used to validate.
https://github.com/localstack/localstack-terraform-samples/tree/master/apigateway-lambda-velocity
pattern = "arn:aws:ssm:%s:%s:parameter/%s"
    param_name = param_name.lstrip("/")
    return _resource_arn(param_name, pattern, account_id=account_id, region_name=region_name)
def s3_bucket_arn(bucket_name_or_arn: str, account_id=None):
    bucket_name = s3_bucket_name(bucket_name_or_arn)
    return "arn:aws:s3:::%s" % bucket_name
def s3_bucket_name(bucket_name_or_arn: str) -> str:
    return bucket_name_or_arn.split(":::")[-1]
def _resource_arn(name: str, pattern: str, account_id: str = None, region_name: str = None) -> str:
    if ":" in name:
        return name
    account_id = get_account_id(account_id)
    region_name = region_name or get_region()
    if len(pattern.split("%s")) == 3:
        return pattern % (account_id, name)
    return pattern % (region_name, account_id, name)
def get_events_target_attributes(target):
    return pick_attributes(target, EVENT_TARGET_PARAMETERS)
def get_or_create_bucket(bucket_name, s3_client=None):
    s3_client = s3_client or connect_to_service("s3")
    try:
        return s3_client.head_bucket(Bucket=bucket_name)
    except Exception:
        return s3_client.create_bucket(Bucket=bucket_name)
def create_sqs_queue(queue_name, env=None):