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
```
return
        executor = lambda_api.LAMBDA_EXECUTOR
        func_name = 'test_destroy_idle_containers'
        func_arn = lambda_api.func_arn(func_name)
        
        executor.destroy_existing_docker_containers()
        self.assertEqual(len(executor.get_all_container_names()), 0)
        
        testutil.create_lambda_function(
            func_name=func_name, handler_file=TEST_LAMBDA_ENV, libs=TEST_LAMBDA_LIBS,
            runtime=LAMBDA_RUNTIME_PYTHON27, envvars={'Hello': 'World'})
        self.assertEqual(len(executor.get_all_container_names()), 0)
        self.lambda_client.invoke(FunctionName=func_name, Payload=b'{}')
        self.assertEqual(len(executor.get_all_container_names()), 1)
        
        executor.idle_container_destroyer()
        self.assertEqual(len(executor.get_all_container_names()), 1)
        
        executor.function_invoke_times[func_arn] = time.time() - lambda_executors.MAX_CONTAINER_IDLE_TIME_MS
        executor.idle_container_destroyer()
        self.assertEqual(len(executor.get_all_container_names()), 0)
        
        testutil.delete_lambda_function(func_name)
class Util(object):
    @classmethod
    def create_function(cls, file, name, runtime=None, libs=None):
        runtime = runtime or LAMBDA_RUNTIME_PYTHON27
        testutil.create_lambda_function(
            func_name=name, handler_file=file, libs=TEST_LAMBDA_LIBS, runtime=runtime)