### 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_
if not cls.INSTANCES:
            classes = get_all_subclasses(LambdaExecutorPlugin)
            cls.INSTANCES = [clazz() for clazz in classes]
        return cls.INSTANCES
class LambdaInvocationForwarderPlugin(LambdaExecutorPlugin):
    """Plugin that forwards Lambda invocations to external targets defined in LAMBDA_FORWARD_URL"""
    def should_apply(self, context: InvocationContext) -> bool:
        """If LAMBDA_FORWARD_URL is configured, forward the invocation of this Lambda to the target URL."""
        func_forward_url = self._forward_url(context)
        return bool(func_forward_url)
    def prepare_invocation(
        self, context: InvocationContext
    ) -> Optional[Union[AdditionalInvocationOptions, InvocationResult]]:
        forward_url = self._forward_url(context)
        result = self._forward_to_url(
            forward_url,
            context.lambda_function,
            context.event,
            context.context,
            context.invocation_type,
        )
        return result
    def _forward_to_url(
        self,
        forward_url: str,
        lambda_function: LambdaFunction,
        event: Union[Dict, bytes],
        context: LambdaContext,
        invocation_type: str,
    ) -> InvocationResult: