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
```
expected = ['.*Custom Runtime Lambda handler executing.']
        self.check_lambda_logs(
            TEST_LAMBDA_NAME_CUSTOM_RUNTIME, expected_lines=expected)
        
        testutil.delete_lambda_function(TEST_LAMBDA_NAME_CUSTOM_RUNTIME)
class TestDotNetCoreRuntimes(LambdaTestBase):
    @classmethod
    def setUpClass(cls):
        cls.lambda_client = aws_stack.connect_to_service('lambda')
        cls.zip_file_content2 = load_file(TEST_LAMBDA_DOTNETCORE2, mode='rb')
        cls.zip_file_content31 = load_file(TEST_LAMBDA_DOTNETCORE31, mode='rb')
    def __run_test(self, func_name, zip_file, handler, runtime, expected_lines):
        if not use_docker():
            return
        testutil.create_lambda_function(
            func_name=func_name,
            zip_file=zip_file,
            handler=handler,
            runtime=runtime)
        result = self.lambda_client.invoke(FunctionName=func_name, Payload=b'{}')
        result_data = result['Payload'].read()
        self.assertEqual(result['StatusCode'], 200)
        self.assertEqual(to_str(result_data).strip(), '{}')
        
        
        testutil.delete_lambda_function(func_name)
    def test_dotnetcore2_lambda_running_in_docker(self):
        self.__run_test(
            func_name=TEST_LAMBDA_NAME_DOTNETCORE2,
            zip_file=self.zip_file_content2,