### Is there an existing issue for this?

- [X] I have searched the existing issues

### Feature description

The use case I have in mind is to run Node 16.x Lambdas - the default container registry is `lambci/lambda` which is effectively abandoned. [Not even Node 14.x has been published](https://github.com/lambci/docker-lambda/pull/330). However, switching the registry over to [`amazon/aws-lambda-nodejs`](https://hub.docker.com/r/amazon/aws-lambda-nodejs) still fails to pull the container, since localstack is looking for the tag `nodejs16.x`. I'd like to be able to specify that if the runtime is `nodejs16.x` it just looks for tag `16`.

### 🧑‍💻 Implementation

_No response_

### Anything else?

_No response_
temp_mv_dict = defaultdict(list)
    for key in elements:
        if isinstance(key, (list, tuple)):
            key, value = key
        else:
            value = elements[key]
        key = to_str(key)
        temp_mv_dict[key].append(value)
    return dict((k, tuple(v)) for k, v in temp_mv_dict.items())
def get_lambda_runtime(runtime_details: Union[LambdaFunction, str]) -> str:
    """Return the runtime string from the given LambdaFunction (or runtime string)."""
    if isinstance(runtime_details, LambdaFunction):
        runtime_details = runtime_details.runtime
    if not isinstance(runtime_details, str):
        LOG.info("Unable to determine Lambda runtime from parameter: %s", runtime_details)
    return runtime_details or ""
def is_provided_runtime(runtime_details: Union[LambdaFunction, str]) -> bool:
    """Whether the given LambdaFunction uses a 'provided' runtime."""
    runtime = get_lambda_runtime(runtime_details) or ""
    return runtime.startswith("provided")
def format_name_to_path(handler_name: str, delimiter: str, extension: str):
    file_path = handler_name.rpartition(delimiter)[0]
    if delimiter == ":":
        file_path = file_path.split(delimiter)[0]
    if os.path.sep not in file_path:
        file_path = file_path.replace(".", os.path.sep)
    if file_path.startswith(f".{os.path.sep}"):
        file_path = file_path[2:]
    return f"{file_path}{extension}"
def get_handler_file_from_name(handler_name: str, runtime: str = None):