### 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
region_details = APIGatewayRegion.get()
    api_id = get_api_id_from_path(path)
    authorizer_id = get_authorizer_id_from_path(path)
    auth_list = region_details.authorizers[api_id]
    for i in range(len(auth_list)):
        if auth_list[i]["id"] == authorizer_id:
            del auth_list[i]
            break
    return make_accepted_response()
def handle_authorizers(method, path, data, headers):
    if method == "GET":
        return get_authorizers(path)
    if method == "POST":
        return add_authorizer(path, data)
    if method == "PATCH":
        return update_authorizer(path, data)
    if method == "DELETE":
        return delete_authorizer(path)
    return make_error_response("Not implemented for API Gateway authorizers: %s" % method, code=404)
def get_documentation_part_id_from_path(path):