### 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
"""Return 'value' if it is not None, or 'alternative' otherwise."""
    return value if value is not None else alternative
def recurse_object(obj: ComplexType, func: Callable, path: str = "") -> ComplexType:
    """Recursively apply `func` to `obj` (may be a list, dict, or other object)."""
    obj = func(obj, path=path)
    if isinstance(obj, list):
        for i in range(len(obj)):
            tmp_path = "%s[%s]" % (path or ".", i)
            obj[i] = recurse_object(obj[i], func, tmp_path)
    elif isinstance(obj, dict):
        for k, v in obj.items():
            tmp_path = "%s%s" % ((path + ".") if path else "", k)
            obj[k] = recurse_object(v, func, tmp_path)
    return obj
def keys_to_lower(obj: ComplexType, skip_children_of: List[str] = None) -> ComplexType:
    """Recursively changes all dict keys to first character lowercase. Skip children
    of any elements whose names are contained in skip_children_of (e.g., ['Tags'])"""
    skip_children_of = ensure_list(skip_children_of or [])
    def fix_keys(o, path="", **kwargs):
        if any(re.match(r"(^|.*\.)%s($|[.\[].*)" % k, path) for k in skip_children_of):
            return o
        if isinstance(o, dict):
            for k, v in dict(o).items():
                o.pop(k)
                o[first_char_to_lower(k)] = v
        return o
    result = recurse_object(obj, fix_keys)
    return result