### 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
kinesis = connect_to_service("kinesis", env=env)
    result = []
    response = kinesis.get_shard_iterator(
        StreamName=stream_name, ShardId=shard_id, ShardIteratorType="TRIM_HORIZON"
    )
    shard_iterator = response["ShardIterator"]
    while shard_iterator:
        records_response = kinesis.get_records(ShardIterator=shard_iterator)
        records = records_response["Records"]
        for record in records:
            try:
                record["Data"] = to_str(record["Data"])
            except Exception:
                pass
        result.extend(records)
        shard_iterator = records_response["NextShardIterator"] if records else False
        while len(result) > count:
            result.pop(0)
    return result
def get_stack_details(stack_name, region_name=None):
    cloudformation = connect_to_service("cloudformation", region_name=region_name)
    stacks = cloudformation.describe_stacks(StackName=stack_name)
    for stack in stacks["Stacks"]:
        if stack["StackName"] == stack_name:
            return stack
def deploy_cf_stack(stack_name, template_body):