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
```
type(None): ('n',),
    int: ('0', '1', '2', '3', '4', '5', '6', '7', '8', '9'),
    float: ('0', '1', '2', '3', '4', '5', '6', '7', '8', '9')
}
POSSIBLE_JSON_TYPES = (str, bytes)
JSON_START_TYPES = tuple(set(JSON_START_CHAR_MAP.keys()) - set(POSSIBLE_JSON_TYPES))
JSON_START_CHARS = tuple(set(functools.reduce(lambda x, y: x + y, JSON_START_CHAR_MAP.values())))
SQS_LISTENER_THREAD = {}
SQS_POLL_INTERVAL_SEC = 1
LAMBDA_EXECUTOR = lambda_executors.AVAILABLE_EXECUTORS.get(config.LAMBDA_EXECUTOR, lambda_executors.DEFAULT_EXECUTOR)
IAM_POLICY_VERSION = '2012-10-17'
POLICY_NAME_PATTERN = 'lambda_policy_%s'
BUCKET_MARKER_LOCAL = '__local__'
class ClientError(Exception):
    def __init__(self, msg, code=400):
        super(ClientError, self).__init__(msg)
        self.code = code
        self.msg = msg
    def get_response(self):
        if isinstance(self.msg, Response):
            return self.msg
        return error_response(self.msg, self.code)
class LambdaContext(object):
    def __init__(self, func_details, qualifier=None):
        self.function_name = func_details.name()
        self.function_version = func_details.get_qualifier_version(qualifier)
        self.invoked_function_arn = func_details.arn()
        if qualifier:
            self.invoked_function_arn += ':' + qualifier
    def get_remaining_time_in_millis(self):