### 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_
import json
import logging
import os
from typing import Optional, Union
from localstack import config
from localstack.services import install
from localstack.services.awslambda.lambda_executors import (
    AdditionalInvocationOptions,
    InvocationContext,
    InvocationResult,
    LambdaExecutorPlugin,
    is_java_lambda,
    is_nodejs_runtime,
)
from localstack.services.awslambda.lambda_utils import (
    LAMBDA_RUNTIME_JAVA8,
    LAMBDA_RUNTIME_JAVA8_AL2,
    LAMBDA_RUNTIME_JAVA11,
    LAMBDA_RUNTIME_NODEJS10X,
    LAMBDA_RUNTIME_NODEJS12X,
    LAMBDA_RUNTIME_NODEJS14X,
    LAMBDA_RUNTIME_PYTHON36,
    LAMBDA_RUNTIME_PYTHON37,
    LAMBDA_RUNTIME_PYTHON38,
    get_executor_mode,
    is_python_runtime,
)
from localstack.utils import common