### 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
"""Simple wrapper class that allows us to create a hashset using the object id(..) as the entries' hash value"""
    def __init__(self, obj):
        self.obj = obj
        self._hash = id(obj)
    def __hash__(self):
        return self._hash
    def __eq__(self, other):
        
        return self.obj == other.obj
class SubtypesInstanceManager:
    """Simple instance manager base class that scans the subclasses of a base type for concrete named
    implementations, and lazily creates and returns (singleton) instances on demand."""
    _instances: Dict[str, "SubtypesInstanceManager"]
    @classmethod
    def get(cls, subtype_name: str, raise_if_missing: bool = True):
        instances = cls.instances()
        base_type = cls.get_base_type()
        if not instances:
            for clazz in get_all_subclasses(base_type):
                instances[clazz.impl_name()] = clazz()
        instance = instances.get(subtype_name)
        if not instance and raise_if_missing:
            raise NotImplementedError(
                f"Unable to find implementation named '{subtype_name}' for base type {base_type}"
            )
        return instance
    @classmethod
    def instances(cls) -> Dict[str, "SubtypesInstanceManager"]: