### 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
assert is_none_or_empty(obj) == result
@pytest.mark.parametrize(
    ["obj", "result"],
    [
        ([], True),
        (None, True),
        ([1], False),
        (["1", "2"], False),
    ],
)
def test_is_none_or_empty_lists(obj, result):
    assert is_none_or_empty(obj) == result
def test_run_cmd_as_str_or_list():
    def _run(cmd):
        return run(cmd).strip()
    
    
    assert "foo bar 123" == _run("echo 'foo bar 123'")
    assert "foo bar 123" == _run("echo foo bar 123")
    assert "foo bar 123" == _run("  echo    foo    bar     123    ")
    assert "foo bar 123" == _run(["echo", "foo bar 123"])
    assert "foo bar 123" == _run(["echo", "foo", "bar", "123"])
    with pytest.raises(FileNotFoundError):
        _run(["echo 'foo bar 123'"])
@pytest.mark.parametrize("tail_engine", ["command", "tailer"])