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
```
'OnFailure': {
                'Destination': str(response.dead_letter_config)
            }
        }
    })
@app.route('/2019-09-25/functions/<function>/event-invoke-config', methods=['GET'])
def get_function_event_invoke_config(function):
    """ Retrieves the configuration for asynchronous invocation for a function
        ---
        operationId: GetFunctionEventInvokeConfig
        parameters:
            - name: 'function'
              in: path
            - name: 'qualifier'
              in: path
            - name: 'request'
              in: body
    """
    try:
        function_arn = func_arn(function)
        lambda_obj = arn_to_lambda[function_arn]
    except Exception as e:
        return error_response(str(e), 400)
    response = lambda_obj.get_function_event_invoke_config()
    return jsonify(response)
def serve(port, quiet=True):
    
    LAMBDA_EXECUTOR.startup()
    generic_proxy.serve_flask_app(app=app, port=port, quiet=quiet)