### 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
match = re.match(PATH_REGEX_TEST_INVOKE_API, path)
            invocation_context.method = match[3]
            if data:
                orig_data = data
                path_with_query_string = orig_data.get("pathWithQueryString", None)
                if path_with_query_string:
                    invocation_context.path_with_query_string = path_with_query_string
                invocation_context.data = data.get("body")
                invocation_context.headers = orig_data.get("headers", {})
            result = invoke_rest_api_from_request(invocation_context)
            result = {
                "status": result.status_code,
                "body": to_str(result.content),
                "headers": dict(result.headers),
            }
            return result
        return True
    def return_response(self, method, path, data, headers, response):
        
        if re.match(r"/restapis/[^/]+/documentation/versions", path):
            if response.status_code == 404:
                return requests_response({"position": "1", "items": []})
        
        if response.status_code == 404:
            data = data and json.loads(to_str(data))
            result = None
            if path == "/account":
                result = handle_accounts(method, path, data, headers)