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.assertIn(':policy/', matching[0]['Arn'])
        
        resp = lambda_client.remove_permission(FunctionName=TEST_LAMBDA_NAME_PY,
                                               StatementId=resp['Statement'], Qualifier='qual1', RevisionId='r1')
        self.assertEqual(resp['ResponseMetadata']['HTTPStatusCode'], 200)
    def test_event_source_mapping_default_batch_size(self):
        function_name = 'lambda_func-{}'.format(short_uid())
        queue_name_1 = 'queue-{}-1'.format(short_uid())
        queue_name_2 = 'queue-{}-2'.format(short_uid())
        ddb_table = 'ddb_table-{}'.format(short_uid())
        testutil.create_lambda_function(
            handler_file=TEST_LAMBDA_ECHO_FILE,
            func_name=function_name,
            runtime=LAMBDA_RUNTIME_PYTHON36
        )
        lambda_client = aws_stack.connect_to_service('lambda')
        sqs_client = aws_stack.connect_to_service('sqs')
        queue_url_1 = sqs_client.create_queue(QueueName=queue_name_1)['QueueUrl']
        queue_arn_1 = aws_stack.sqs_queue_arn(queue_name_1)
        rs = lambda_client.create_event_source_mapping(
            EventSourceArn=queue_arn_1,
            FunctionName=function_name
        )
        self.assertEqual(rs['BatchSize'], BATCH_SIZE_RANGES['sqs'][0])
        uuid = rs['UUID']
        try:
            
            lambda_client.update_event_source_mapping(
                UUID=uuid,
                FunctionName=function_name,