### 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:logs:%s:%s:log-group:%s"
    return _resource_arn(group_name, pattern, account_id=account_id, region_name=region_name)
def events_rule_arn(rule_name, account_id=None, region_name=None):
    pattern = "arn:aws:events:%s:%s:rule/%s"
    return _resource_arn(rule_name, pattern, account_id=account_id, region_name=region_name)
def lambda_function_arn(function_name, account_id=None, region_name=None):
    return lambda_function_or_layer_arn(
        "function", function_name, account_id=account_id, region_name=region_name
    )
def lambda_layer_arn(layer_name, version=None, account_id=None):
    return lambda_function_or_layer_arn("layer", layer_name, version=None, account_id=account_id)
def lambda_function_or_layer_arn(
    type, entity_name, version=None, account_id=None, region_name=None
):
    pattern = "arn:aws:lambda:.*:.*:(function|layer):.*"
    if re.match(pattern, entity_name):
        return entity_name
    if ":" in entity_name:
        client = connect_to_service("lambda")
        entity_name, _, alias = entity_name.rpartition(":")
        try:
            alias_response = client.get_alias(FunctionName=entity_name, Name=alias)
            version = alias_response["FunctionVersion"]
        except Exception as e:
            msg = "Alias %s of %s not found" % (alias, entity_name)
            LOG.info(f"{msg}: {e}")
            raise Exception(msg)
    account_id = get_account_id(account_id)