As an enhancement to https://github.com/localstack/localstack/pull/1194

It would be really helpful to send the Lambda name, either as data, a header, or as part of the URL.

At code location: https://github.com/localstack/localstack/blob/03c6f4bf250edd18eb818ed65090f508636b0bff/localstack/services/awslambda/lambda_api.py#L696

I can likely open a PR to handle this given some feedback on the feature and potential design.

Right now all I see is the following (using `npx http-echo-server`):
```
[socket#8] event: data
--> POST / HTTP/1.1
--> Host: 192.168.1.x:3000
--> User-Agent: python-requests/2.22.0
--> Accept-Encoding: gzip, deflate
--> Accept: */*
--> Connection: keep-alive
--> Content-Length: 9
--> Content-Type: application/x-www-form-urlencoded
-->
-->
[socket#8] event: data
--> Name=test
```
---
        operationId: 'invokeFunction'
        parameters:
            - name: 'request'
              in: body
    """
    
    arn = func_arn(function)
    
    m = re.match('(arn:aws:lambda:.*:.*:function:[a-zA-Z0-9-_]+)(:.*)?', arn)
    if m and m.group(2):
        qualifier = m.group(2)[1:]
        arn = m.group(1)
    else:
        qualifier = request.args.get('Qualifier')
    data = request.get_data()
    if data:
        data = to_str(data)
        try:
            data = json.loads(data)
        except Exception:
            try:
                
                data = json.loads(parse_chunked_data(data))
            except Exception:
                return error_response('The payload is not JSON: %s' % data, 415,
                                      error_type='UnsupportedMediaTypeException')
    
    invocation_type = request.environ.get('HTTP_X_AMZ_INVOCATION_TYPE', 'RequestResponse')
    def _create_response(result, status_code=200):