### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

`#return` macro for AppSync is not supported

```
- ["Error in template '<string>' at position 48-60 in expression: #return($v1)\nException: no such macro: return\n\nGraphQL request:3:11\n2 |         {\n3 |           hi2 {\n  |           ^\n4 |             value"] None
```

### Expected Behavior

`#return` is a valid command in AppSync Resolver Velocity request and response templates.

https://docs.aws.amazon.com/appsync/latest/devguide/aws-appsync-directives.html 

### How are you starting LocalStack?

With the `localstack` script

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

    localstack start

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

1. `CDKDeployment`
2. GraphQL Rest API to `localstack`

3. AppSync resolver with response template:

```vtl
#set($v1 = {})
$util.qr($v1.put('value', 'hi'))
#return($v1)"
```

```sdl
schema {
  query: Query
}
type valueObj {
  value: String
}
type Query {
  hi2: valueObj
}
```

4. Query AppSync

```sdl
Query {
   hi2
}
```



### Environment

```markdown
- OS: Ubuntu/WSL2
- LocalStack: 0.14.2.1
```


### Anything else?

The same code runs fine on AWS/AppSync.
if not isinstance(s, str):
            s = json.dumps(s)
        encoded_str = s.encode(config.DEFAULT_ENCODING)
        encoded_b64_str = base64.b64encode(encoded_str)
        return encoded_b64_str.decode(config.DEFAULT_ENCODING)
    def base64Decode(self, s):
        if not isinstance(s, str):
            s = json.dumps(s)
        return base64.b64decode(s)
    def toJson(self, obj):
        return obj and json.dumps(obj)
    def urlEncode(self, s):
        return quote_plus(s)
    def urlDecode(self, s):
        return unquote_plus(s)
    def escapeJavaScript(self, s):
        try:
            return json.dumps(json.loads(s))
        except Exception:
            primitive_types = (str, int, bool, float, type(None))
            s = s if isinstance(s, primitive_types) else str(s)
        if str(s).strip() in ["true", "false"]:
            s = bool(s)
        elif s not in [True, False] and is_number(s):
            s = to_number(s)
        return json.dumps(s)
class VelocityInput: