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
```
self.assertEqual(result['StatusCode'], 202)
        self.assertEqual(to_str(result_data).strip(), '')
    def test_stream_handler(self):
        result = self.lambda_client.invoke(
            FunctionName=TEST_LAMBDA_NAME_JAVA_STREAM, Payload=b'{}')
        result_data = result['Payload'].read()
        self.assertEqual(result['StatusCode'], 200)
        self.assertEqual(to_str(result_data).strip(), '{}')
    def test_serializable_input_object(self):
        result = self.lambda_client.invoke(
            FunctionName=TEST_LAMBDA_NAME_JAVA_SERIALIZABLE,
            Payload=b'{"bucket": "test_bucket", "key": "test_key"}')
        result_data = result['Payload'].read()
        self.assertEqual(result['StatusCode'], 200)
        self.assertDictEqual(
            json.loads(to_str(result_data)),
            {'validated': True, 'bucket': 'test_bucket', 'key': 'test_key'}
        )
class TestDockerBehaviour(LambdaTestBase):
    @classmethod
    def setUpClass(cls):
        cls.lambda_client = aws_stack.connect_to_service('lambda')
    def test_prime_and_destroy_containers(self):
        
        if not isinstance(lambda_api.LAMBDA_EXECUTOR,
                          lambda_executors.LambdaExecutorReuseContainers):
            return
        executor = lambda_api.LAMBDA_EXECUTOR
        func_name = 'test_prime_and_destroy_containers'
        func_arn = lambda_api.func_arn(func_name)