### 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_
event: LambdaEvent
    lambda_command: Union[str, List[str]]  
    docker_flags: Union[str, List[str]]  
    environment: Dict[str, Optional[str]]
    context: LambdaContext
    invocation_type: str  
    def __init__(
        self,
        lambda_function: LambdaFunction,
        event: LambdaEvent,
        environment=None,
        context=None,
        lambda_command=None,
        docker_flags=None,
        function_version=None,
        invocation_type=None,
    ):
        self.lambda_function = lambda_function
        self.handler = lambda_function.handler
        self.event = event
        self.environment = {} if environment is None else environment
        self.context = {} if context is None else context
        self.lambda_command = lambda_command
        self.docker_flags = docker_flags
        self.function_version = function_version
        self.invocation_type = invocation_type
class LambdaExecutorPlugin:
    """Plugin abstraction that allows to hook in additional functionality into the Lambda executors."""
    INSTANCES: List["LambdaExecutorPlugin"] = []
    def initialize(self):